STUDIES IN THE PHYSICAL CHEMISTRY OF THE PROTEINS.
|
|
- Bertram Moody
- 5 years ago
- Views:
Transcription
1 STUDIES IN THE PHYSICAL CHEMISTRY OF THE PROTEINS. V. THE MOLECULAR WEIGHTS OF THE PROTEINS.* PART 1. THE MINIMAL MOLECULAR WEIGHTS OF CERTAIN PROTEINS. BY EDWIN J. COHN, JESSIE L. HENDRY, AND ADELA M. PRENTISS. (Prom the Department of Physical Chemistry in the Laboratories of Physiology, Harvard Medical School, Boston.) (Received for publication, February 11, 1925.) CONTENTS. PAoE I. Introduction Determination of molecular weights by means of osmotic pressuremeasurements Determination of minimal molecular weights by means of combining and containing weights II. Calculation of the minimal molecular weights of proteins from their composition Iron content of hemoglobin Copper content of hemocyanin Sulfur content of proteins Sulfide sulfur content of proteins Phosphorus content of proteins Tryptophane content of proteins Tyrosine and cystine contents of proteins Histidine, arginine, and lysine contents of proteins III. Calculation of the minimal molecular weights of proteins from their equivalent weights Saturation of proteins with gases % Saturation of proteins with acids or bases determined by electromotive force measurements Combination of proteins with acids and bases determined by solubility measurements * The results of this investigation were reported at the meeting of the American Society of Biological Chemists, at Washington, D. C., December, 1924 (11). 721
2 722 Physical Chemistry of Proteins. V IV. Minimal molecular weights of certain proteins IIemoglobin Hemocyanin Egg albumin Casein Zein Gliadin Glutenin Gelatin F,destin Serum globulin Serum albumin E ibrin Bence-Jones protein V. Discussion VI. Summary I. INTRODUCTION. The large molecular weights of the proteins must be considered one of their outst,anding characteristics, in great part responsible for such colloidal asp&s of their behaviour as their failure to pass through many natural and artificial membranes. It is probably because of their size that proteins are retained by cell walls through which their constituent parts and their decomposition products freely pass. The cellular structure of biological systems, and their stability under changing metabolic condit,ions, depends, therefore, upon the separat,ion and the concentration of large organic molecules within limiting membranes. Many natural plant and animal cells were utilized in the development of our modern theory of solutions, because of t.he permeability of their cell walls to small organic and inorganic molecules, and their impermeability to such of their constituents as the proteins. In the classical paper before the Swedish Academy in which van t Hoff applied the gas laws to solutions by demonstrating the relation between osmotic pressure and the number of dissolved molecules, the argument rested in part upon De Vries measurements of the plasmolysis of plant cells, in part upon Hamburger s measurements of the hemolysis of blood corpuscles, and in part upon Pfeffer s experiments with artificial
3 Cohn, Hendry, and Prentiss 723 membranes (72). In the former, natural cells served as osmometers; in the latter, artificial cells, impermeable to certain molecules, allowed of the direct measurement of the osmotic pressures they produced. Determination of Molecular Weights by Means of Osmotic Pressure Measurements.-Since natural and artificial cells could be used as delicate indicators of the osmotic pressure of solutions, it was natural to suppose that measurements of the osmotic pressures of such constituents of cells as the proteins might lead to exact knowledge of their molecular weights and volumes. Sorensen and his collaborators have recently determined the molecular weight of egg albumin (70), serum albumin, and serum globulin with great accuracy by measurements of osmotic pressure. These investigators took into account sources of error involved in such measurements, which were not completely understood by earlier workers. These depend upon the reactivity and the multivalent character of the proteins, and upon the dissociation of the different compounds that proteins form with each other and with acids, bases, and salts. As a result of these complications, measurements of the osmotic pressures of proteins have not always led to consistent estimates of their molecular weights. The measurements on hemoglobin solutions of Reid, Htifner and Gansser, Roaf, and of Adair illustrate this contention. Reid (66) prepared the haemoglobin by crystallisation and obtained a pressure of about 4 millitnetres of mercury for each 1 per cent. of haemoglobin 3 or a molecular weight of over 42,000. Hiifner and Gansser (41), on the other hand, found the molecular weight of horse hemoglobin to be approximately 15,000, and of ox hemoglobin 16,000. The great effect of the solvent upon the osmotic pressures of hemoglobin solutions was first indicated by Roaf (67), and has since been systematically studied for other proteins by Lillie (48), and for hemoglobin by Adair (3). In Roaf s investigation three deter- 1 Sorensen, S. P. L., personal communication. * Different compounds of the same protein exert different pressures both because of the different number of particles into which they dissociate, and because of the complicated membrane equilibria which arise whenever the memhrane is permeable to certain of the ions of such compounds, and impermeable to others (50). 3 Roaf (67), p. i.
4 724 Physical Chemistry of Proteins. V minations of osmotic pressure were made, the first with distilled water, the second with 0.34 per cent. sodium bicarbonate (0.04 N) and the third with 0.2 per cent. sodium carbonate (0.04N). The osmotic pressures obtained for 1 per cent. haemoglobin were 5.7, 5.3 and 11.6 millimctres of mercury respectively. These pressures correspond to aggregates of 29787, 32035, and It should be noted that Roaf s lowest value for the molecular weight of hemoglobin in the presence of sodium carbonate was of the same order as IIiifner and Gansser s value. In this case the haemoglobin aggregate corresponds to its molecular weight calculated from the amount of iron present.3 Where the molecular weight is higher, it has been assumed that the hemoglobin existed in aggregates. Lillie s (48), Sorensen s (70), and Loeb s (50) investigations of the osmotic pressures of other proteins render it more probable that the lowest pressures correspond to those produced by the uncombined protein, while the higher pressures represent the dissociation of protein compounds with their attendant membrane equilibria. Determination of Minimal Molecular Weights by imeans of Combining and Containing Weights.-With the development of the modern theory of solutions, it was inevitable that the measurement of the osmotic pressures of protein solutions should seem the best method for the determination of their molecular weights. In the last 30 years such investigations have revealed complications which depended upon phenomena that are only now beginning to be understood, and that have thus far been adequately considered in but few researches. Meanwhile there has accumulated a vast body of analytical information regarding the composition of proteins on the basis of which their minimal molecular weights can be calculated, and a large number of physicochemical methods on the basis of which their equivalent combining weights can bc determined. In the succeeding sections of this paper the evidence that can be derived from the simultaneous consideration of the analytical and physical chemistry of the proteins will be considered. In a subsequent communication the relative size of the molecules of a series of proteins will be determined by the method of dialysis or ultrafiltration (7), and their probable molecular weights estimated as integral multiples of their
5 Cohn, Hendry, and Prentiss 725 minimal molecular weights. This procedure of estimating molecular weights as multiples of minimal molecular weights has often been followed in classical inorganic and organic chemistry. II. Calculation of the Minimal MolecuLr Weights of Proteins from Their Composition. Whereas great uncertainty exists concerning the true molecular weight of hemoglobin, the equivalent combining weight of this protein, and consequently its minimal molecular weight has bsen accurately known for 30 years. In 1894 Hiifner (39) studied the carbon monoxide-combining capacity of the hemoglobin of the ox, and found that 16,721 gm. of hemoglobin combined with each mol of carbon monoxide. Oxygen combines with the same amount of hemoglobin as does carbon monoxide (63). It is therefore certain that these important physiological reactions proceed stoichiometrically. Iron Content of Henzoglobin.-Hemoglobin contains iron. Zinoffsky, Hiifner, Jaquet, and Abderhalden have determined the amount of iron contained in the hemoglobin of different species. Their results indicate that hemoglobin always contains between and 0.40 per cent of iron, and at the same time suggest the first indirect method of estimating the minimal molecular weight of a protein in terms of a well known constituent of its molecule. For if the per cent of iron in the hemoglobin molecule of the horse represents but 1 gm. atom of iron, the molecular weight of the protein must be approximately 16,669. The relation upon which calculations of this type depend is expressed by the equat,ion Minimal molecular weight of protein = ~~r~~n~~~~:~~~r~e~ (1) Precise est,imates of minimal molecular weights, based upon actual determinations of the iron content of the hemoglobins of different species, are contained in Table I. Copper Content of Hemocyanin.-The proteins of the blood of certain of the Mollusca and Arthropoda contain copper, which presumably subserves the same function as the iron of hemo-
6 726 Physical Chemistry of Proteins. V globin. These proteins, because of their blue color, are all termed hemocyanins. The different amounts of copper in the hemocyanins of different genera and phyla indicate molecular weights that arc not identical (64). Further investigation has demonstrated that these copper-containing proteins differ not only in their minimal molecular weights, but in many other respects (5). Sulfur Content of Proteins.-Hemoglobin, hemocyanin, and many other proteins contain sulfur. Analyses of the sulfur contents of proteins, therefore, offer another method of estimating their minimal molecular weights. In the case of hemoglobin and hemocyanin, consideration of the sulfur content has for the most part confirmed t.he molecular weights postulated on the basis of the iron analysis. Occasionally, however, as in the case of the sulfur content of the hemoglobin of the ox, the sulfur analysis suggests that the molecular weight may be at least twice that demanded by the iron analysis. Sulfide A%&u- Content of Proteins.-The large amount of sulfur that many proteins contain diminishes the usefulness of the analysis of total sulfur, for the smallest weights of proteins that can contain 1 atom of sulfur arc often too small a fraction of their minimal molecular weights to aid in their estimation. Part of the sulfur in the protein molecule is,. however, sulfide sulfur; estimated by means of its lead-blackening property (53). T. B. Osborne (58) has studied the ratio of sulfide sulfur to total sulfur in a series of proteins, and has shown that the sulfide sulfur usually represents an integral fraction of the total sulfur. On the basis of this relation, Osborne estimated that the molecular weights of many proteins were in the neighborhood of 30,000 (57). The sulfide sulfur in the protein molecule has been supposed to represent, at least in part, the sulfur either in the ammo acid cystine or cystcine. Cysteine contains but 1 atom of sulfur, while cystine contains 2. Whatever the nature of the sulfide sulfur, it represents an integral part of the protein molecule, and the quantities that analyses reveal can be used in estimating the minimal molecular weights of proteins, in the same manner as can their iron, copper, or total sulfur content. Phosphorus Content of Proteins.-Certain proteins contain small amounts of phosphorus. Casein contains both sulfur and phosphorus, and the amounts of these two elements have led to
7 Cohn, Hendry, and Prentiss 727 almost identical estimates of the minimal molecular weight of this protein at 4,220 and 4,372 respectively (47, 8). Tryptophane Content of Proteins.-The tryptophane content of casein suggests that its molecular weight must be some multiple of the minimal molecular weight deduced from its phosphorus or sulfur content. Tryptophane exists in the casein molecule to the extent of 1.5 per cent according to the earlier analysts (59), 1.54 per cent according to Folin and Looney (21), and 1.7 per cent according to Dakin (16). The lower figure substituted in a relation similar to equation (1) leads to a molecular weight of 13,606; the higher, to 12,006. The average, 12,806, is three times the weight calculated from the phosphorus or from the sulfur content of casein. A minimal molecular weight of this order enabled us, in a previous communication (14), to approximate the molecular composition of casein. This molecule contains but 2 molecules of histidine, 3 of arginine and phenylalanine, and 4 of aspartic acid and tyrosine. The amino acids present in larger amounts can also be calculated, but cannot be considered as giving further evidence regarding the size of the molecule. That the assumption of this number of amino acid molecules leads to a minimal molecular weight near 12,800 gm. is demonstrated by the calculation in Table IV. Tryptophane is present in many protein molecules to a smaller extent than nearly any amino acid except cystine. Its quantitative isolation and estimation have, however, been difficult. In recent years numerous calorimetric methods have been evolved for determining the amount of this amino acid, as well as of tyrosine and of cystine, in protein hydrolysates. These methods avoid the losses that occur in the separation and quantitative estimation of amino acids. The excellent agreement between the tryptophane content of casein, as estimated by Folin and Looney, and the yields that have been obtained by isolation has already been alluded to. Tyrosine and Cystine Contents of Proteins.-Folin and Looney (21) have estimated the tryptophane, tyrosine, and cystine contents of a large number of proteins, and a number of other investigators have estimated these amino acids in different proteins, either by these or by other calorimetric methods. Whether
8 728 Physical Chemistry of Proteins. V cysteine or cystine exists in the protein molecule is still a debated question, but the form that is usually isolated from protein hydrolysates is cystine. If cysteine is present in the protein, the minimal molecular weight would, of course, be half that calculated from the cystine analyses. Histidine, Arginine, and Lysine Contents of Proteins.--Van Slyke s (71) nitrogen distribution method of determining the diamino acids in proteins also avoids the losses often attendant upon the separation and gravimetric estimation of amino acids. Moreover, many proteins contain but a small number of molecules of either histidine, arginine, or lysine. Accordingly, we have recalculated his results from nitrogen as per cent of nitrogen to per cent of protein, and included them in our tabulation of significant data for the determination of molecular weights.4 The yields of certain amino acids, determined by the classical methods, have occasionally been included. The internal evidence offered by the data here presented is such that this procedure is less arbitrary than it may appear. For when the minimal molecular weights, calculated on the basis of a number of constituents of the same molecule, lead to values that are related to each other in definite and integral proportions, the results attain a significance which is greater than can be claimed for an individual analysis. Finally, if the equivalent combining weights of the proteins, determined by one of the physicochemical methods that we shall now consider, yield results that are also consistent with the minimal molecular weights, calculated by analytical methods, a body of evidence accumulates which can scarcely be considered fortuitous. III. Calculation of the M inimal Molecular Weights of Proteins from Their Equivalent Weights. Saturation of Proteins,with Gases.--ilny stoichiometric reaction involving a protein may be utilized in estimating its equivalent weight. From the equivalent combining weight of the 4 D. Jordan Lloyd (49) has previously attempted to determine the molecular weight of gelatin from Van Slyke s data. Her method was different from that here employed.
9 Cohn, Hendry, and Prentiss 729 reagent, the amount required to saturate or combine a given weight of the protein can be calculated by means of the relation Equivalent combining n-eight of protein Weight of combined protein Equivalent weight of reagent = iiightofcombined reagent G9 Certain proteins which are involved in the transport of oxygen in the body, such as the hemoglobins and the hemocyanins, combine chemically with oxygen, and some also with carbon monoxide. From the carbon monoxide-combining capacity of hemoglobin, Ilufner early estimated that its minimal molecular weight was 16,721 (39). His result was, as we have seen, in excellent agreement with the weight of hemoglobin that contained 1 atom of iron. As early as 1894 the minimal molecular mcight of a protein had, therefore, been determined by the simultaneous consideration of analytical and physicochemical evidence. Saturation of Proteins with Acids or Bases Determined by Electromotiz;e Force Measurements.-Whereas only certain specialized proteins combine with gases, all proteins combine with acids or with bases. The amount of acid or base with which a protein can combine depends in the last analysis upon its composition and structure (12, 13, 25). Without reference to the nature of the groups involved in these reactions, the amount of combination at saturation of the protein can be utilized for the calculation of its equivalent combining weight, by means of the relation expressed in equation (2). The electromotive force methods for determining the maximum acid- or base-combining capacity of proteins have been considered in detail by Robertson (68), Pauli (62), and more recently by Hitchcock (34, 35), by Greenberg and Schmidt (27), and by us (12). Robertson determined in this way the equivalent combining weight for base of cnsein, serum globulin, and ovomucoid. A recalculation of Hitchcock s potential measurements has yielded the combining capacities of gelatin and edestin. Greenberg and Schmidt have also studied the base-combining capacity of gelatin, casein, and gliadin. These results have been considered in calculating minimal molecular weights wherever the protein did not contain so many groups as to lead to too low an equivalent weight. Bracewell (9) also measured the acid-combining capacity of a few proteins in connection with his attempt to show that this
10 Physical Chemistry of Proteins. V property depended upon their lysine and arginine, but not upon their histidine content. His method was less accurate than the electrometric procedure that has generally been employed. The reason for this will be considered in another place in connection with a study of the relation between the diamino acids in proteins and their acid-combining capacity.6 For completeness we have often included Bracewell s values, and considered them in the estimation of the equivalent combining weights of the proteins. In the case of a few proteins the total number of acid or of basic groups is so low that their equivalent combining weights at saturation are of great value in the calculation of their minimal molecular weights. This is t,rue of the acid groups in zein, gliadin, gelatin, and egg albumin, and of the basic groups in gliadin. In most proteins, however, the number of acid or basic groups is so large as to render measurements of their acid- or base-combining capacities at saturation almost valueless for this purpose. Combination of Proteins with Acids and Bases Determined by Solubility Measurements.-Many proteins are very insoluble when uncombined with acid or base. Thus casein only dissolves in water to the extent of 0.11 gm., serum globulin to the extent of 0.07 gm. (II), and zein to the extent of 0.05 gm. in 1 liter (13). Certain of the globulins, the glutelins, and the prolamins, all of which are relatively insoluble in water, have very wide precipitation zones. These appear to form insoluble compounds with acids and with bases. This must occur in the case of proteins like zein and gliadin which do not pass into solution until very alkaline reactions are reached, but which nevertheless combine base at neutral reactions. It would appear that these proteins dissolve only after neutralization of all their base-combining groups. In one series of experiments with zein, the addition of two-thirds of the maximal base-combining capacity resulted in the solution of less than one-tenth of the protein present. The base must have combined with the zein to form one or more insoluble compounds. T. B. Osborne (56) as early as 1902 studied the amount of acid required to form an insoluble hydrochloride of neutral edestin. He showed that the combining weight of protein, as 6 Cohn, E. J., and Berggren, R. E. L., unpublished data.
11 Cohn, Hendry, and Prentiss 731 calculated from an analysis of the amount of acid in this compound, was a multiple of the minimal molecular weight calculated from its sulfur content. Here, again, the simultaneous consideration of the composition of a protein, and of its reactions, has yielded an accurate estimate of its minimal molecular weight. When slight,ly larger amounts of acid or of base are added to certain proteins in the neighborhood of their isoelectric points, an amount of protein passes into solution which is proportional to the base added. Measurements of the solubility of edestin in systems containing protein in excess and known concentrations of base or of acid were also made by Osborne (56).. More recently WC have studied the solubility of cascin and of serum globulin in such systems. The weight of protein dissolved in combination with the reagent can be calculated from the increased solubility produced by increments of base by means of equation (2). Only a few of the many free groups that such proteins contain usually dissociate in the neighborhood of their isoelectric points. Small amounts of reagent, therefore, combine with large amounts of the protein. As a result equivalent combining weights, calculated from solubility measurements, are of inestimable value in calculating the minimal molecular weights of slightly soluble proteins. Up to the present, the equivalent weights only of casein and of serum globulin have been accurately determined by the solubility method. Bence-Jones protein has also been studied to some extent, and the equivalent weights of other proteins should presently be available. Meanwhile it seemed desirable to report the methods that are being employed and the results that have thus far been obtained, together with the analytical information that has been collected. IV. Minimal Molecular Weights of Certnin Proteins. Hemoglobin.-Hemoglobin was the first protein whose minimal molecular weight was adequately determined. Moreover, five different methods have been employed in its estimation by a score of different investigators. In the latter part of the last century, Zinoffsky and, later, Hiifner, and Jaquet (42) studied the iron and sulfur contents of
12 732 Physical Chemistry of Proteins. V the hemoglobins of a large number of species. Their analyt,ical results are summarized in Table I. In all of the six species considered, the hemoglobin contained between and 0.40 per cent, of iron. Taking the atomic weight of iron as 55.54, the weight of protein containing 1 atom of iron has been calculated by means of the relation Atomic weight of iron X 100 Minimal molecular weight of Hb = -Percentf ;ron in Hb (3) These analytical results indicate that the minimal molecular weights of the hemoglobins are not identical. The hemoglobin of the pig appears to have the smallest minimal molecular weight, 13,960, and of the horse and fowl the largest, 16,669. The minimal molecular weights of the hemoglobins of the ox and of the dog are essentially identical to the latter, or 16,619. This difference is, of course, smaller than the experimental error, and it might therefore be argued that all hemoglobins had the same molecular weight, and that the higher percentage of iron in the cat and pig were due to experimental error. The sulfur contents of the hemoglobins of these same species not only give additional information regarding the minimal molecular weights of these proteins, but also demonstrate differences in the hemoglobins of different species quite as conclusively as the more recent investigations of Reichert and Brown (65) and of Landsteiner and Heidelbcrger (46). The weight of hemoglobin containing 1 atom of sulfur is in every case lower than the weight containing 1 atom of iron. As a result, the hemoglobin molecule must contain a larger number of atoms of sulfur than of iron. The ratio of iron atoms to sulfur atoms in the hemoglobin of the horse and of the pig is as 1:2. On the basis of 2 atoms of sulfur in horse hemoglobin, its molecular weight must be 16,878, which is in excellent agreement with the value calculated from its iron content, 16,669. The agreement in the case of pig hemoglobin is almost as satisfactory, although the minimal molecular weight would appear to be different. The ratio of iron atoms to sulfur atoms in the hemoglobin of the dog and of the cat is, however, as 1:3. The differences in these iron-sulfur ratios constitute conclusive evidence that the hemoglobins of these species cannot be identical.
13 Cohn, Hendry, and Prentiss 733 The analyses of Hiifner and of Jaquet, which have elsewhere led to such consistent results, do not yield a simple ratio of iron atoms to sulfur atoms in the hemoglobin of the ox or of the fowl, TABLE I. Minimal Molecular Weights of the Hemoglobins. Method. Horse. Pig. cat. ox. Fowl. Dog. Iron content (73). Sulfide sulfur (69). Sulfur I (73). Iron I Sulfur Iron Sulfur < CO-combining capacity (39). Iron content (39). Sulfur (33). (54). Arginine (71). Iron Sulfur I per ceni gm , , , , , ,446 (38) , ,960 (38) , ,362 ( 1) , ,954 ( 1) , , (42) ,669 (42) ,729 Iron (42) ,619 Sulfide sulfur (57) ,573 Sulfur (42) ,646 16, ,442 16, ,238 7, ,635 6, ,405 4, ,356 33,338 33,561 49,857 47,865 50,814 on the basis of a molecular weight in the neighborhood of 16,700.6 However, if it be assumed that the molecular weight is twice as great, or approximately 33,400, then the ratio of iron atoms to sulfur atoms in ox hemoglobin becomes 2:s and in fowl hemo- BMtiller (54) gives 0.48 per cent for the sulfur content of ox hemoglobin, referring presumably to an article of Htifner s (39). In an earlier article (38) Hiifner gives the sulfur content of ox hemoglobin as
14 734 Physical Chemistry of Proteins. V globin 2: 9. As a result, these.t,wo instances not only add further evidence regarding t,he specificity of the hemoglobins of different species, but indicate that the molecular weight of this protein must be greater than 16,700, at least in certain forms. The carbon monoxide-combining capacity of ox hemoglobin also led Hiifner to a minimal molecular weight of 16,721 for this protein. This value is almost identical with that derived from its iron content, and Peters (63) has since demonstrated that the oxygen-combining capacity of hemoglobin was also proportional to its iron content. The osmotic pressure determinations of Hiifner and Gansser (41) and of Roaf (67) that were carried out in alkaline solution indicated molecular weights of the order of 16,000. Roaf s determinations of the osmotic pressure of hemoglobin in distilled water and in sodium bicarbonate, however, indicated molecular weights of 29,787 and 32,035. Adair s recent measurements with horse and human hemoglobin, which have been corrected for the Donnan equilibrium, indicate still higher molecular weights. These results suggest, for reasons already indicated in the first sections of this paper, that the true molecular weight of hemoglobin is at least 33,400, and that the higher osmotic pressures that have occasionally led investigators to postulate lower molecular weights are to be explained as due either to dissociation of hemoglobin in alkaline solution, or to the membrane equilibria attending such dissociation. There is evidence, however, that the molecular weight, of certain hemoglobins may be higher than 33,400. Weymouth Reid (66) estimated the molecular weight of recrystallized dog hemoglobin by the osmotic pressure method. He obtained slightly higher osmotic pressures with twice recrystallized hemoglobin than with hemoglobin that had been recrystallized but once. Measurements upon the latter indicated a molecular weight of approximately 48,000, while his results with the twice recrystallized protein led to only a slightly lower value in the neighborhood of 42,000. Osborne (57) has determined the sulfide sulfur in the hemoglobin of the dog. His estimate made in 1902 one can probably rely upon.... as reasonably accurate. The smallest weight 7 Personal communication.
15 Cohn, Hendry, and Prentiss of dog hemoglobin that can, on the basis of this determination, contain 1 gm. atom of sulfide sulfur would be 9,573 gm. The smallest molecular weight that can be postulated for dog hemoglobin on the basis of the simultaneous consideration of both the iron and the sulfide sulfur contents is five times the latter value, or approximately 47,865, a result which is in good agreement with that calculated from Reid s determination of the osmotic pressure of the same species. The analytical evidence becomes still more consistent if it be assumed that the dog hemoglobin molecule contains 4 atoms of iron, 7 of sulfide sulfur, and 12 of sulfur. The molecular weights calculated on this basis from these t hree hemoglobin constituents are 66,476, 67,011, and 67,752.s As a result of studies of the oxygen-combining capacity of hemoglobin in the presence either of carbonic acid or of base, Adair has suggested that the molecule of hemoglobin may contain 4 atoms of iron and, therefore, have a molecular weight of 66,800. Finally Van Slyke (71) has determined the argininc, histidine, and lysine contents of ox hemoglobin, and Hanke and Kocssler (30) the histidine content of ox, horse, and cat hemoglobin. Only in the case of the arginine was the content of the amino acid low enough to yield a sufficiently high value for the weight of the protein containing 1 molecule, to be considered significant in the estimation of its molecular weight. The smallest weight of ox hemoglobin that can contain 1 molecule of arginine is 4,107 gm. Four times this value equals 16,428 gm., and eight times equals 32,856 gm., results which are in fair agrcemcnt with the molecular weight calculated above. Hemocyanin.-Since the copper and sulfur contents of the hemocyanins of various forms are different, it follows that their molecular weights must also be different. The difference between the hemocyanins of certain Cephalopoda and Arthropoda is particularly striking. Thus the hemocyanin of Octopus contains more copper than does that of Limulus, while the latter * That the true molecular weight of the hemoglobins not only of the dog, but also of the ox and of the horse, is either50,000 or G7,OOO will be shown in a subsequent communication. Ultrafiltration and dialyzing experiments have shown that hemoglobin is larger than serum albumin (7), and that these three hemoglobins have very similar molecular dimensions.
16 736 Physical Chemistry of Proteins. V contains nearly twice as much sulfur as the former. According to Henze (33) Octopus hemocyanin contains 0.38 per cent of copper. A calculation similar to that employed with the iron of hemoglobin leads to a molecular weight for this protein of 16,729. The sulfur content, 0.86 per cent, indicates that the smallest weight that can contain 1 atom of that element must be 3,729. Four times 3,729 leads to a much lower value for the minimal molecular weight than that estimated from its copper content. Five times 3,729 leads to a value that is too high. If these analytical values are assumed to be correct, the smallest Oclopus. Limulus. - - TABLE Minimal Molecular TVei$hts of the Hemocyanins. Method. Copper content (33). Sulfur (33). Copper ( 5). Arginine (71). Sulfur ( 5). Lysine (71). Histidine (71). II. per cent elm , , ,704 2,198 2,056 2,040 1, ,458 33,561 22,704 21,980 22,, ) ,813 molecular weight that can be attributed to this protein must be 33,500. For if it is assumed that this hemocyanin molecule contains 2 atoms of copper, its weight becomes 33,458; and if it contains 9 atoms of sulfur, it becomes 33,561. We may, therefore, take the minimal molecular weight of this protein as 33,500. A similar calculation has been made on the basis of Alsberg and Clark s analysis (5) of copper and of sulfur in the hemocyanin of Limulus, and is reported in Table II. The hi&line, arginine, and lysine contents of Limulus hemocyanin determined by Van Slyke (71) have also been used in this calculation. The minimal molecular weight of this substance is unquestionably different
17 Cohn, Hendry, and Prentiss 737 from that of the hemocyanm of Octopus, as Alsberg maintained, and is probably 22,700. For a summary of analyses and of containing weights of various hemocyanins, reference may be made to the article by Quagliariello (64). Egg Albumin.-At the time these investigations were undertaken, egg albumin was the only protein whose molecular weight had been adequately estimated from the osmotic pressure which TABLE Minimal Molecular Weight of Egg Albumin. Method. Osmotic pressure (70). Cystine content (31). I (43). Tryptophane (21). Histidine (60). Sulfide sulfur I (57). Aspartic acid I (60). Tyrosine (21). Lysine I (60). Arginine (60). Phenylalanine I (60). Proline (60). Sulfur I (57). Maximal base-combining capacity.6 III ,76C , , ,07c , ,05C 4.2 4, , , , , ,934 1,250-1 i 1 1, I,,, I - 34, , , , , , , , , , , , , ,750 it produces in the neighborhood of its isoelectric point. As a result of a painstaking series of investigations, in which corrections for membrane equilibria were employed, S. P. L. Sorensen and his collaborators (70) came to the conclusion that the molecular weight of egg albumin was approximately 34,000. Folin and Looney estimated the tryptophane and tyrosine contents of egg albumin as 1.23 and 4.2 per cent respectively. On the basis of the tryptophane content, the molecular weight of egg albumin must be at least 16,593. Twice this value, or 33,186,
18 738 Physical Chemistry of Proteins. V is in excellent agreement with the molecular weight calculated by Sorensen from osmotic pressure measurements. A molecule of egg albumin that contains 8 molecules of tyrosine would, by a similar calculation, have a molecular weight of 34,496. Any difference in the assumed number of tyrosine molecules leads to a dif?erence of over 4,000 in the calculated molecular weight. Therefore, this determination also confirms the estimate of the molecular weight of egg albumin. Egg albumin also contains cystine, but Folin and Looncy do not report a determination of the amount of this amino acid present. Harris (31) has estimated that egg albumin contains at least per cent of cystine, and more recently Jones, Gersdorff, and Moeller (43) have found 0.88 per cent, using Folin and Looney s calorimetric method. On this basis, the molecular weight would bc greater than 27,000, a result which cannot be considered as quantitatively satisfactory, but which nevertheless furnishes evidence of the size of this molecule. There is more sulfide sulfur in egg albumin, as in edestin and casein, than can be accounted for on the basis of its cystine content. Osborne (57) has determined both the sulfide sulfur and the total sulfur contents. There is too large an amount of total sulfur in egg albumin to render its determination of great value in minimal molecular weight calculations. If, however, one assumes that the egg albumin molecule contains 5 atoms of sulfide sulfur, its molecular weight becomes 32,660. The fact that a molecule of this size contains 1 molecule of cystinc or 2 of cysteine, and a prime number of sulfide sulfur and of sulfur atoms, makes the estimate of its minimal molecular weight independent of, but in excellent agreement with, Sorensen s osmotic pressure measurements. In 1909 Osborne, Jones, and Leavenworth (60) completed an analysis of the hydrolytic products of this protein. Their results for histidine, arginine, aspartic acid, phenylalanine, and proline, which have been included in Table III, all support the conclusion of Sorensen, that the molecular weight of egg albumin is approximately 34,000. The tryptophane, tyrosine, and sulfur determinations render 33,800 the most probable value. Casein.-The minimal molecular weight of casein also depends in large part upon its tryptophane content (21). Until recently the minimal molecular weight of casein has generally been assumed
19 Cohn, Hendry, and Prentiss 739 to be approximately 4,300. This estimate has been based on its phosphorus and on its sulfur contents. In a recent investigation, Cohn and Hendry (14) have determined, by the solubility method, that the equivalent combining capacity of casein for NaOH, in the neighborhood of its isoelectric point, lies between 2,006 and 2,166 gm. In another investigation, Cohn and Berggren (12) have determined, by means of electromotive force measurements, that TABLE IV. Minimal Molecular Weight Method. Tryptophane content (21). I (16). Histidine (59). I (30). Phosphorus ( 8). Sulfur I (29, 47). Phenylalanine I (22). Arginine S (59). Tyrosine (21). (20). Aspartic acid (1 3. Equivalent base-combining capacity (14). /%Hydroxyglutamic acid content (16). Ammonia I (59). Cystine I Sulfide sulfur of Casein.,er cent mn. 3, , , , , , , , , , , , , , ,253 12,006 12,408 10,922 13,116 12,660 12,765 13,710 13,516 12,556 12,984.2,600.2,424 12,696 (21) , ,080 (43) , ,384 (57) l,i52 3 )5,256 the maximal base-combining capacity of casein was 546 gm. Four times the equivalent combining weight at saturation yields 2,184 gm., a value which is in good agreement with the equivalent combining weight for base near the isoelectric point. The equivalent weight derived from solubi1it.y measurements is more accurate than that derived from electromotive force measurements. Six times the lower estimate derived from solubility
20 Physical Chemistry of Proteins. V measurements equals 12,576, and six times the higher equals 12,996. The molecular weight derived from Folin and Looney s tryptophanc determination is 13,253, and that derived from Dakin s gravimetric determination is 12,006. Six times the average of the limiting combining weights is 12,786, and of the tryptophane-containing weights is 12,629. Therefore, 12,800 may be taken as the minimal molecular weight of casein. Besides tryptophane, casein contains several other amino acids in such small amounts that they render still more certain this estimate of its minimal molecular weight. A casein molecule of this size would contain 2 molecules of histidine, 3 of phenylalanine and arginine, and 4 of tyrosine and aspartic acid. The minimal molecular weight calculated from each of these component parts of the casein molecule falls between 12,400 and 13,700. Two component parts of the casein molecule indicate that its true molecular weight must bc larger than, and some multiple of, 12,500. Osborne (57) long since determined the sulfide sulfur content of casein. A molecule of casein containing but 1 atom of sulfide sulfur must weigh 31,752 gm. Folin and Looney (21) find as little as 0.25 per cent of cystinc in casein, and Jones, Gersdorff, and Moeller (43), using the same method, have found almost precisely the same amount, 0.26 per cent. -4 molecule of casein containing 1 molecule of cystine, or 2 of cysteine, must therefore weigh approximately 96,000 gm. Such a molecule would contain 3 sulfide sulfur atoms, for three times 31,752 equals 95,256. The sulfide sulfur and the cystine contents of casein indicate that its minimal molecular weight must be far greater than 12,800, the value at which we arrived from t,he consideration of the other amino acids that casein contains and from its combining capacity. If we multiply this accurately known minimal molecular weight by 7, the result is, however, not in very good agreement with the molecular weight postulated from the sulfide sulfur or the cystine content. Eight times the minimal molecular weight leads to a result which is in no better agreement. If we proceed tentatively on the basis of these analytical results, allowing ourselves to be persuaded of their accuracy because of t,heir consistency, we must consider the molecular weight of casein as fifteen times 12,800, or 192,000. This estimate is precisely twice that demanded by
21 Cohn, Hendry, and Prentiss 741 the cystine, or four times that demanded by the cysteine, content of this protein. We have long hesitated to assume so great a molecular weight as 192,000 for any protcin.g It is impossible, however, to reconcile these different analytical results on the basis of a smaller molecule. Zein.-In considering the relation between the composition of zein and its acid and basic properties, we have recently had occasion to estimate its minimal molecular weight from a simultaneous consideration of its composition and its base-combining capacity. Cystine and histidine would seem to be the amino acids in which zein is poorest. If zcin contains 0.8 per cent of histidinc the molecular weight of zein cannot bc less than 1 3, There is some reason to believe that no very great change will occur in this estimate of the minimal molecular weight. For if the zcin molecule contains 2 molecules of arginine its weight would be 19,344; 3 molecules of P-hydroxyglutamic acid bring the molecular weight to 19,752; 3 of aspartic acid to 22,182; and 4 atoms of sulfur to 21,380. Although it is probable that all of these values will change as methods of separation and analysis improve, the very high known percentage composition of zein on the one hand, and the frequency with which a small number of assumed molecules leads to a molecular weight near 20,000 allows us to assume a figure of this order for the minimal molecular weight of zein with a fair degree of probability (13). Measurements of the base-combining capacity of zcin lead to an equivalent weight which is approximately one-sixth as great as the minimal molecular weight postulated on the basis of its histidine content. Two zein preparations were studied, one of which bound and the other mol of sodium hydroxide per gram (13). The equivalent weights of zein bound by 1 mol of sodium hydroxide were, therefore, 3,226 and 3,571 respectively. Six times the former leads to a minimal molecular weight of 19,356, and six times the latter combining weight. t o 21,426. These resuks must be considered in fair agreement with t.he minimal molecular weight estimated from analyses of zein. The true molecular weight of zein may be very much larger than 20,000. Folin and Looney have found only 0.5 per cent of cystine in zein hydrolysates by their calorimetric method. If this estimate is correct the molecular weight cannot be less than 48,040. Osborne had previously found that zein contained but a small amount of sulfide sulfur, and had accordingly predicted a high molecular weight. He found but per cent.of sulfide 9 See Cohn and Hendry (14), p, 549.
22 742 Physical Chemistry of Proteins. V sulfur. On the basis of this determination 15,127 gm. of zein would contain but 1 such atom. Three times this value leads to a molecular weight of 45,381, which is in good agreement with the molecular weight postulated on the basis of the cystine content. This coincidence lends a certain weight to both values, and also suggests that all of the sulfide sulfur in zein cannot represent cyst&e (13). I- T4nT.z v. Minimal Molecular Weight Zein. Method. Histidine content (61). Arginine (44). Aspartic acid (19). &Hydroxyglutamic acid (19). I Sulfur (57). Tyrosine (21). Rlaximal base-combining capacity (13). er cent Qrn. 1.8,91i 9,56t 7,391 6,522 5,34i 3,234 3,4Ol Cystine content (43). 0.85!8,25! Histidinc < (61). 0.82!8,91! Sulfide sulfur I (57). 0.21: 15,12: Arginine (44) ,56t Aspartic acid (19) ,39< Sulfur (57) ,34! I Cystine Histidine Sulfide sulfur I Arginine Aspartic acid Sulfur (21). 0.5 (61) L 3 K!3,04( 18,91! (57). 0.21:!I 15,12 (44) ,561 (19) ,391 (57) ,34! 1 18, , , , , , , , , , , , , , , , , , ,210 Since these calculations were made, Jones, Gersdorff, and Moeller (43) have reported a cystine content in zein of 0.85 per cent. If this higher result is correct the cystine-containing weight is 28,259. Such a molecule would contain 2, rather than 3, sulfide sulfur atoms. In zein, as in cascin, the cystine content suggests a higher molecular weight than does any other amino acid. For neither
23 Cohn, Hendry, and Prentiss 743 of the minimal molecular weights calculated from these different analyses of cystine is an integral multiple of 19,400. Jones, Gersdorff, and Moeller s cystine determination leads to a minimal molecular weight of approximately 58,000; Folin and Looney s to one of 96,000. Both would contain 2 cystine or 4 cysteine molecules, whiie the former would contain 3, the latter 5, histidine molecules. The physicochemical and analytical data have been calculated and tabulated on both bases. The weights of zein containing sulfur and aspartic acid, which in the first computation led to slightly abnormal values, conform admirably to a minimal molecular weight of approximately 58,000 or 96,000. Nevertheless the discrepancy between the cystine estimates is such that it seems preferable, pending its redetermination, to consider 19,400 as the minimal molecular weight of zein. G&ad&.-The minimal molecular weight of gliadin can be estimated with great precision both by analytical and by physicochemical means. The very small number of free acid and free basic groups in the prolamins renders electromotive force measurements of their equivalent weights particularly valuable in the estimation of their minimal molecular weights. The tryptophane content of gliadin has been determined both gravimetrically and calorimetrically. Abderhalden and Samuely (2) found approximately 1 per cent of tryptophane in gliadin, Folin and Looney (21) estimated that a slightly larger amount was present, namely 1.14 per cent, and Cross and Swain (15) found 1.11, 1.19, 1.03, and 1.13 per cent in preparations from different flours. May and Rose (52), using a comparative colorimetric method based upon the amount of tryptophane in casein, estimated that gliadin contained 1.05 per cent. Since casein probably contains nearer 1.6 than 1.5 per cent, their results are probably low by about 6 per cent. These four different investigations leave little doubt that gliadin contains between 1.0 and 1.14 per cent of tryptophane. The minimal molecular weight of gliadin Gahhted from the lowest value is 20,410, and from 1.14 per cent is 17,904.lO 10 If Folin and Looney s tryptophane and cystine estimates are both correct, the molecular weight of gliadin cannot be less than 72,000. The sulfur content of gliadin leads to a containing weight which also suggests 72,000 rather than 20,700, but the lysine content would demand a molecule of twice this size.
24 744 Physical Chemistry of Proteins. V The lysine content of gliadin is also very small. Van Slyke s most recently published determination of this quantity, 0.69 per cent (71), leads to a minimal molecular weight of 21,173. The tryptophane and lysine contents of gliadin, therefore, suggest a minimal molecular weight in the neighborhood of 20,000. A number of other amino acids are present in gliadin in very TABLE Minimal Molecular Weight of Gliadin. Method. Tryptophane content (21). I ( 2). Lysine (71). Cystine I (21). &Hydroxyglutamic acid (17). Sulfide sulfur (57). Histidine I (71). Arginine (71). Tyrosine (21). Maximal base-combining capacity (25). < Sulfur content (57; VI. er cent Qrn..7,901 to, 41(!1,17Z 0,35: 6,79( 5,181 4,63f 5,544 5,174 3,33: 3,441 3,12: %3 3 2.P 2 o- 1 17, , , , , , , , , , ,688 7 ~_ 21,861 small amount. Thus, Folin and Looney s cystine determination (21) leads to a minimal molecular weight of 10,353, and Jones, Gersdorff, and Moeller s (43) lower determinations, to slightly higher values. On the basis of Folin and Looney s estimate, 2 molecules of cystine, or 4 of cysteine lead to a minimal molecular weight of 20,706; 3 of P-hydroxyglutamic acid, to 20,388; and 11 Cross and Swain have used Van Slyke s method in estimating the diamino acids. Whereas the sum of the average results for all these acids is equal to the sum of the histidine, arginine, and lysine determinations of Van Slyke, the variations between their different analyses were so great as to preclude their use in the calculation of containing weights. Their tyrosine values are doubtless a little high owing to the residual color of the reagent (15), and are therefore not considered.
SELENIUM IN PROTEINS FROM TOXIC FOODSTUFFS*
SELENIUM IN PROTEINS FROM TOXIC FOODSTUFFS* III. THE REMOVAL OF SELENIUM FROM TOXIC PROTEIN WDROLYSATES BY E. PAGE PAINTER AND KURT W. FRANKE (From the Department of Experiment Station Chemistry, South
More informationSTUDIES ON GLUTELINS. (Received for publication, March 2, 1927.)
STUDIES ON GLUTELINS. I. THE 01- AND,8-GLUTELINS OF WHEAT (TRITICUM VULGARE).* BY FRANK A. CSONKA AND D. BREESE JONES. (From the Protein Investigation Laboratory, Bureau of Chemistry, United States Department
More informationTHE ASSIMILATION OF AMMONIA NITROGEN BY THE TOBACCO PLANT: A PRELIMINARY STUDY WITH ISOTOPIC NITROGEN. (Received for publication, July 3, 1940)
THE ASSIMILATION OF AMMONIA NITROGEN BY THE TOBACCO PLANT: A PRELIMINARY STUDY WITH ISOTOPIC NITROGEN BY HUBERT BRADFORD VICKERY AND GEORGE W. PUCHER (Prom the Biochemical Laboratory of the Connecticut
More informationTHE METABOLISM OF SULFUR.
THE METABOLISM OF SULFUR. XVI. DIETARY FACTORS IN RELATION TO THE CHEMICAL COMPOSITION OF THE HAIR OF THE YOUNG WHITE RAT. BY HOWARD D. LIGHTBODY AND HOWARD B. LEWIS. (From the Laboratory of Physiological
More informationTHE EFFECT OF VARIOUS ACIDS ON THE DIGESTION OF PROTEINS BY PEPSIN.
Published Online: 20 July, 1919 Supp Info: http://doi.org/10.1085/jgp.1.6.607 Downloaded from jgp.rupress.org on August 20, 2018 THE EFFECT OF VARIOUS ACIDS ON THE DIGESTION OF PROTEINS BY PEPSIN. BY J.
More informationTHE EFFECT OF DENATURATION ON THE VISCOSITY OF PROTEIN SYSTEMS BY M. L. ANSON A~D A. E. MIRSKY. (Accepted for publication, December 2, 1931)
THE EFFECT OF DENATURATION ON THE VISCOSITY OF PROTEIN SYSTEMS BY M. L. ANSON A~D A. E. MIRSKY (From tke Laboratories of The Rockefeller Institute for Medical Research, Princeton, N. Y., and the ttospital
More informationThe source of protein structures is the Protein Data Bank. The unit of classification of structure in SCOP is the protein domain.
UNIT 14 PROTEINS DEFINITION A large molecule composed of one or more chains of amino acids in a specific order; the order is determined by the base sequence of nucleotides in the gene that codes for the
More informationGas Exchange in the Tissues
Gas Exchange in the Tissues As the systemic arterial blood enters capillaries throughout the body, it is separated from the interstitial fluid by only the thin capillary wall, which is highly permeable
More informationCRYSTALLINE PEPSIN BY JOHN H. NORTHROP. (From the Laboratories of The Rockefeller Institute for Medical Research, Princeton, iv. J.
CRYSTALLINE PEPSIN III. PREPARATION OF ACTIVE CRYSTALLINE PEPSIN FROM INACTIVE DENATURED PEPSIN BY JOHN H. NORTHROP (From the Laboratories of The Rockefeller Institute for Medical Research, Princeton,
More informationQUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS
QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS Amino acids are molecules containing an amine group, a carboxylic acid group and a side chain that varies between different amino acids. Amino acids of
More informationQualitative test of protein-lab2
1- Qualitative chemical reactions of amino acid protein functional groups: Certain functional groups in proteins can react to produce characteristically colored products. The color intensity of the product
More informationmethods, and materials used have been the same as those previously described.
AMINO ACIDS IN THE NUTRITION OF EXCISED TOMATO ROOTS PHILIP R. WHITE (WITH FIVE FIGURES) Introduction A preliminary study of the growth-promoting materials obtainable from yeast and essential for the nutrition
More informationCRYSTALLINE PEPSIN V. ISOLATION OF CRYSTALLINE PEPSIN FROM BOVINE GASTRIC JUICE BY JOHN H. NORTHROP
CRYSTALLINE PEPSIN V. ISOLATION OF CRYSTALLINE PEPSIN FROM BOVINE GASTRIC JUICE BY JOHN H. NORTHROP (From the Laboratories of The Rockefeller Institute for Medical Research, Princeton, N. J.) (Accepted
More informationTHE EQUILIBRIUM BETWEEN ACTIVE NATIVE TRYPSIN AND INACTIVE DENATURED TRYPSIN
Published Online: 20 January, 1934 Supp Info: http://doi.org/10.1085/jgp.17.3.393 Downloaded from jgp.rupress.org on November 8, 2018 THE EQUILIBRIUM BETWEEN ACTIVE NATIVE TRYPSIN AND INACTIVE DENATURED
More informationTHE EFFECT OF TITANIUM ON THE OXIDATION OF SULFHYDRYL GROUPS BY VARIOUS TISSUES
THE EFFECT OF TITANIUM ON THE OXIDATION OF SULFHYDRYL GROUPS BY VARIOUS TISSUES BY FREDERICK BERNHEIM AND MARY L. C. BERNHEIM (From the Departments oj Physiology and Pharmacology and Biochemistry, Duke
More informationBIOL 347L Laboratory Three
Introduction BIOL 347L Laboratory Three Osmosis in potato and carrot samples Osmosis is the movement of water molecules through a selectively permeable membrane into a region of higher solute concentration,
More informationTHE ESTIMATION OF TRYPSIN WITH HEMOGLOBIN
THE ESTIMATION OF TRYPSIN WITH HEMOGLOBIN BY M. L. ANSON Am) A. E. MIRSKY (From the Laboratories of The Rockefeller Institute for Medical Research, Princeton, N. J., and the Hospital of The Rockefeller
More informationQualitative chemical reaction of functional group in protein
Qualitative chemical reaction of functional group in protein Certain functional groups in proteins can react to produce characteristically colored products. The color intensity of the product formed by
More informationII. THE EFFECT OF THE INGESTION OF GLYCINE ON THE EXCRETION OF ENDOGENOUS URIC ACID.
PURINE METABOLISM. II. THE EFFECT OF THE INGESTION OF GLYCINE ON THE EXCRETION OF ENDOGENOUS URIC ACID. BY A. A. CHRISTMAN AND E. C. MOSIER. (From the Laboratory of Physiological Chemistry, Medical School,
More informationTHE NUTRITIVE PROPERTIES OF KAFIRIN.
THE NUTRITIVE PROPERTIES OF KAFIRIN. BY ALISXT G. I1C)GAN. (From the Llepartmd of Chemistry, Kansas Stnte Ag~ic~cltuml E xperiment Station: Jlanhattan.) (Reeeivcd for publication, November 22, 1917.) Agriculturists
More informationby both esterification and acetylation of the liver concentrate inorganic salts and a source of energy such as glycerol or
BETA ALANINE AS A GROWTH ACCESSORY FOR THE DIPHTHERIA BACILLUS J. HOWARD MUELLER AND SIDNEY COHEN Department of Bacteriology and Immunology, Harvard University Medical School, Boston, Massachusetts Received
More informationExperiment 6: STANDARDIZATION OF A BASE; MASS PERCENT OF AN ACID
Experiment 6: STANDARDIZATION OF A BASE; MASS PERCENT OF AN ACID Introduction The reaction of an acid and a base to form a salt and water is known as neutralization. In this experiment; potassium acid
More informationI) Choose the best answer: 1- All of the following amino acids are neutral except: a) glycine. b) threonine. c) lysine. d) proline. e) leucine.
1- All of the following amino acids are neutral except: a) glycine. b) threonine. c) lysine. d) proline. e) leucine. 2- The egg white protein, ovalbumin, is denatured in a hard-boiled egg. Which of the
More informationAMINO-ACID SYNTHESIS IN THE ANIMAL ORGANISM.
AMINO-ACID SYNTHESIS IN THE ANIMAL ORGANISM. CAN NOR-LEUCINE REPLACE LYSINE FOR THE NUTRITIVE REQUIREMENTS OF THE WHITE RAT? BY HOWARD B. LEWIS AND LUCIE E. ROOT. (From the Laboratory of Physiological
More informationSprint. Revolutionary technology for the rapid, safe and direct determination of protein
Sprint Rapid Protein Analyzer Revolutionary technology for the rapid, safe and direct determination of protein Benefits Its simple to use Fast analysis of all types of food No hazardous chemicals Safer
More informationconductivity after its precipitation indicated that salts had been held freezing point or conductivity than the precipitation of the same
THE EFFECT ON THE MOLECULAR CONCENTRATION AND ELECTRICAL CONDUCTIVITY OF MUSCLE EXTRACTS OF REMOVAL OF THE PROTEIDS. BY G. N. STEWART, Western Reserve University, Cleveland, U.S.A. (Preliminary Note.)
More informationBCH302 [Practical] 1
BCH302 [Practical] 1 Amino acids play a central role: i. As building blocks of proteins. ii. As intermediates in metabolism, converted to specialized products. There are 20 natural amino acids that are
More informationhypothesis has recently been analysed from a mathematical standpoint applied to mixtures of colloid and crystalloid substances contained in a
THE CARBON DIOXIDE CARRYING POWER OF THE CONSTITUENTS OF PLASMA. THE ALKALI RE- SERVE OF BLOOD. BY J. MELLANBY and C. J. THOMAS. (From the Physiological Laboratory, St Thomas's Hospital, S.E.) CONTENTS.
More informationBCM 101 BIOCHEMISTRY Week 4 Practical Chemistry of proteins
BCM 101 BIOCHEMISTRY Week 4 Practical Chemistry of proteins The word protein is derived from the Greek word proteios, which means of primary importance. In fact, proteins plays an important role in all
More informationTHE isolation and availability of crystalline
Unidentified Factors in Poultry Nutrition. PROPERTIES AND PRELIMINARY FRACTIONATION OF A GROWTH FACTOR IN CONDENSED FISH SOLUBLES H. MENGE, C. A. DENTON, J. R. SIZEMORE, R. J. LILLIE AND H. R. BIRD Bureau
More informationON THE COMPOSITION OF URINARY ALBUMIN.* BY FLORENTIN MEDIGRECEANU.
ON THE COMPOSITION OF URINARY ALBUMIN.* BY FLORENTIN MEDIGRECEANU. (From the Hospital of the Rockefeller Institute for Medical Research, New York.) Since the studies of Brown-Sequard, Teissier, L. Brunton,
More informationLAB#23: Biochemical Evidence of Evolution Name: Period Date :
LAB#23: Biochemical Evidence of Name: Period Date : Laboratory Experience #23 Bridge Worth 80 Lab Minutes If two organisms have similar portions of DNA (genes), these organisms will probably make similar
More informationEFFECT OF HIGH SALT CONCENTRATIONS ON COLOR PRODUCTION OF THE BIURET REACTION FOR PROTEIN ANALYSIS
EFFECT OF HIGH SALT CONCENTRATIONS ON COLOR PRODUCTION OF THE BIURET REACTION FOR PROTEIN ANALYSIS HAROLD L. ROSENTHAL, PH.D., AND TOYOKO KAWAKAMI, M.T. (ASC1>) Division of Biochemistry, Department of
More informationUnderstanding a Soil Report
Understanding a Soil Report AGRONOMY SOIL ANALYSIS 1. Soil ph Soil ph is a measure of the acidity in the soil. An acidic soil has a greater amount of hydrogen (H+) ions and a ph below 7.0. Values above
More informationProteins. Dr. Basima Sadiq Jaff. /3 rd class of pharmacy. PhD. Clinical Biochemistry
Proteins /3 rd class of pharmacy Dr. Basima Sadiq Jaff PhD. Clinical Biochemistry a Greek word that means of first importance. It is a very important class of food molecules that provide organisms not
More informationCOMPLEX SALTS OF AMINO ACIDS AND PEPTIDES
COMPLEX SALTS OF AMINO ACIDS AND PEPTIDES II. DETERMINATION OF Z-PROLINE WITH THE AID OF RHODAN- ILIC ACID. THE STRUCTURE OF GELATIN BY MAX BERGMANN (From the Laboratories of The Rockefeller Institute
More informationSOME of the earliest methods of amino
The Amino Acid Content of Fresh and Stored Shell Eggs. II. Arginine, Histidine, Lysine, Methionine, Cystine, Tyrosine, Tryptophan, Phenylalanine, and Proline* ROBERT JOHN EVANS, J. A. DAVIDSON, SELMA L.
More informationSesame seed powder * product is currently being developed. Chia powder * Product nr HP01 HP04 PU01 SS01 CH01 A01 FS01 FS02 P01 P02 R02
Minerals and approved health claims 2 servings of 20 gr/day RDI (EU) mg/ day Source of 15% RDI (mg) Rich in 30% RDI (mg) - Belgian origin Pumpkin Sesame product is currently being developed Chia might
More informationFREEZING POINTS OF ANTI-COAGULANT SALT SOLUTIONS
Published Online: 20 March, 1935 Supp Info: http://doi.org/10.1085/jgp.18.4.485 Downloaded from jgp.rupress.org on October 21, 2018 FREEZING POINTS OF ANTI-COAGULANT SALT SOLUTIONS B~ DAVID I. HITCI~OCK
More informationSTUDIES ON THE CALCIUM-PROTEIN RELATIONSHIP WITH THE AID OF THE ULTRACENTRIFUGE
STUDIES ON THE CALCIUM-PROTEIN RELATIONSHIP WITH THE AID OF THE ULTRACENTRIFUGE II. OBSERVATIONS ON SERUM BY STEPHAN LUDEWIG, ALFRED CHANUTIN, AND A. V. MASKETt (From the Biochemical Laboralory, University
More informationFunctionality of Protein
Protein Polymers of aa:20 different aa Primary structure aa sequence Secondary structure- chains take up conformations which may crosslink to form helices ie α helix and β pleated sheet Tertiary structure-
More informationCLXXX. VEGETABLE. PROTEINS.
CLXXX. VEGETABLE. PROTEINS. I. THE PROTEINS OF DOLICHOS LAB LAB. By DURAISWAMI NARAYANAMURTI AND COIMBATORE VENKATARAMANA RAMASWAMI. From the Department of Biochemistry, Indian Institute of Science, Bangalore,
More informationCereals and grains. Grain anatomy (APK) Simplified milling scheme for wheat 5/23/2012
Cereals and grains Grain anatomy (APK) Bran -- contains much of the fiber and minerals of the grain Germ -- the part of the grain that would become the new plant if the seed were planted. High in protein
More informationPHAR3316 Pharmacy biochemistry Exam #2 Fall 2010 KEY
1. How many protons is(are) lost when the amino acid Asparagine is titrated from its fully protonated state to a fully deprotonated state? A. 0 B. 1 * C. 2 D. 3 E. none Correct Answer: C (this question
More informationCOLORIMETRIC DETERMINATION OF URIC ACID.
COLORIMETRIC DETERMINATION OF URIC ACID. ESTIMATION OF 0.03 TO 0.5 MG. QUANTITIES BY A NEW METHOD. BY J. LUCIEN MORRIS AND A. GARRARD MACLEOD. (From the Biochemistry Laboratory of the School of Medicine,
More informationChemical Nature of the Amino Acids. Table of a-amino Acids Found in Proteins
Chemical Nature of the Amino Acids All peptides and polypeptides are polymers of alpha-amino acids. There are 20 a- amino acids that are relevant to the make-up of mammalian proteins (see below). Several
More informationTHE INFLUENCE OF OPTICAL ISOMERISM ON THE UTILIZATION OF TRYPTOPHANE, HISTIDINE, AND LYSINE FOR GROWTH IN THE MOUSE*
THE INFLUENCE OF OPTICAL ISOMERISM ON THE UTILIZATION OF TRYPTOPHANE, HISTIDINE, AND LYSINE FOR GROWTH IN THE MOUSE* BY JOHN R. TOTTER AND CLARENCE P. BERG (From the Biochemical Laboratory, State University
More informationBIOL 305L Spring 2019 Laboratory Six
Please print Full name clearly: BIOL 305L Spring 2019 Laboratory Six Osmosis in potato and carrot samples Introduction Osmosis is the movement of water molecules through a selectively permeable membrane
More informationEXPERIMENT 3 PROTEIN AND AMINO ACIDS TEST
EXPERIMENT 3 PROTEIN AND AMINO ACIDS TEST 1.0 OBJECTIVE To determine qualitatively and quantitatively presence or absence of protein and amino acid in a sample 2.0 CORRESPONDING COURSE OUTCOME Ability
More informationMicrobial Enhanced Fish Fertilizer Supplement with Vitamins and Nutrients for Plant Health
Microbial Enhanced Fish Fertilizer Supplement with Vitamins and Nutrients for Plant Health INTRODUCTION: MicrobeBio Hydro Activator naturally occurring beneficial organisms, 100% organic proteins, and
More informationNon-protein nitrogen. balance, was dissolved in approximately 50 cc. of distilled water. By the method of Folin and Wu. 251
SOME CHEMICAL STUDIES OF COMMERCIAL BACTERIOLOGICAL PEPTONES JAMES G. McALPINE AND GEORGE D. BRIGHAM From the Department of Animal Diseases, Storrs Agricultural Experiment Station Storrs, Connecticut Received
More informationAMINO ACIDS. Qualitative Tests
AMINO ACIDS Qualitative Tests AMINO ACIDS Amino acid play A central role as building block of proteins. Amino acids also converted to specialized products. More than 300 different amino acids have been
More informationand the cells removed by centrifugation. These were resuspended in sterile 1949a), growth was measured in terms of acid production while dextran was
THE NUTRITIONAL REQUIREMENTS OF LEUCONOSTOC DEXTRANICUM FOR GROWTH AND DEXTRAN SYNTHESIS1 VIRGINIA WHITESIDE-CARLSON AND CARMEN L. ROSANO Biochemistry Department, Medical College of Alabama, Birmingham,
More informationTHE MAINTENANCE OF A NORMAL PLASMA PROTEIN CONCENTRATION IN SPITE OF REPEATED PROTEIN LOSS BY BLEEDING
Published Online: 1 May, 1932 Supp Info: http://doi.org/1.184/jem.55.5.683 Downloaded from jem.rupress.org on September 3, 218 THE MAINTENANCE OF A NORMAL PLASMA PROTEIN CONCENTRATION IN SPITE OF REPEATED
More informationMECHANISM OF INHIBITION OF PHOSPHATASE ACTIVITY BY GLYCINE
MECHANISM OF INHIBITION OF PHOSPHATASE ACTIVIT B GLCINE B OSCAR BODANSK (From the Department of Pharmacology, Cornell University Medical College, New ork City) (Received for publication, July 11, 1946)
More informationGB Translated English of Chinese Standard: GB NATIONAL STANDARD
Translated English of Chinese Standard: GB5009.5-2016 www.chinesestandard.net Sales@ChineseStandard.net GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA GB 5009.5-2016 National food safety standard
More informationAmino acids. Ing. Petrová Jaroslava. Workshop on Official Controls of Feed AGR 46230, , Ankara. Turkey ÚKZÚZ - NRL RO Praha 1
Amino acids Ing. Petrová Jaroslava Workshop on Official Controls of Feed AGR 46230, 6. 7. 12. 2011, Ankara. Turkey 6.12.2011 ÚKZÚZ - NRL RO Praha 1 Content of this presentation 1. Function of amino acids
More informationTHE OCCURRENCE OF AMINO ACIDS AND OTHER OR- GANIC NITROGEN COMPOUNDS IN LAKE WATER.*
THE OCCURRENCE OF AMINO ACIDS AND OTHER OR- GANIC NITROGEN COMPOUNDS IN LAKE WATER.* BY W. H. PETERSON, E. B. FRED, AND B. P. DOMOGALLA. (From the Wisconsin Geological and Natural History Survey and the
More informationCHEMICAL, CLINICAL, AND IMMUNOLOGICAL STUDIES ON THE PRODUCTS
Downloaded from http://www.jci.org on February 1, 218. https://doi.org/1.1172/jci11647 CHEMICAL, CLINICAL, AND IMMUNOLOGICAL STUDIES ON THE PRODUCTS OF HUMAN PLASMA FRACTIONATION. XXIV. STUDIES ON THE
More informationIntroduction to Biochemistry Midterm exam )ومن أحياها(
Introduction to Biochemistry Midterm exam 2016-2017 )ومن أحياها( 1. Which of the following amino (in a peptide chain) would probably be found at a beta bend or turn? a. lysine * b. Gly c. arg d. asn 2.
More informationQuantitative Determination of Proteins
UV-0003 Introduction One of the easiest and most accurate spectroscopic tool for determining protein concentration is by UV-Visible spectrophotometers. The V-630 is designed for biochemical analysis and
More informationChemistry 212. Experiment 3 ANALYSIS OF A SOLID MIXTURE LEARNING OBJECTIVES. - learn to analyze a solid unknown with volumetric techniques.
Experiment 3 The objectives of this experiment are to LEARNING OBJECTIVES - learn to analyze a solid unknown with volumetric techniques. - use stoichiometry to determine the percentage of KHP in a solid
More informationImportant - Please read this before you turn the page.
Midterm Examination - Individual Part Wednesday, 26 March 2008 H. B. White - Instructor Name Important - Please read this before you turn the page. There are 9 pages to this examination including this
More informationFundamentals of Organic Chemistry CHEM 109 For Students of Health Colleges
Fundamentals of Organic Chemistry CHEM 109 For Students of Health Colleges Credit hrs.: (2+1) King Saud University College of Science, Chemistry Department CHEM 109 CHAPTER 9. AMINO ACIDS, PEPTIDES AND
More informationTHE EFFECT OF ROENTGEN RADIATION UPON THE REACTION OF THE FLUID OF RAT SARCOMA 10
THE EFFECT OF ROENTGEN RADIATION UPON THE REACTION OF THE FLUID OF RAT SARCOMA 10 L. C. MAXWELL AND H. J. ULLMANN WITH THE TECHNICAL ASSISTANCE ELLA MAY OTTERY OF (From the Department oj Cancer Research,
More informationAnalyses of Inspection Samples of Fertilizers, Fall 1916.
Analyses of Inspection Samples of Fertilizers, Fall 1916. J. T. WILLARD and R. C. WILEY. THIS circular presents the results of the analyses of inspecttion samples of fertilizers taken from stocks offered
More informationMay 2003: Hemoglobin Red Blood, Blue Blood Use and Abuse of Hemoglobin
Red Blood, Blue Blood Ever wondered why blood vessels appear blue? Oxygenated blood is bright red: when you are cut, the blood you see is brilliant red oxygenated blood. Deoxygenated blood is deep purple:
More informationThe total protein test is a rough measure of all of the proteins in the plasma. Total protein measurements can reflect:
Proteins Part 2 Introduction The total protein test is a rough measure of all of the proteins in the plasma. Total protein measurements can reflect: nutritional status, kidney disease, liver disease, and
More informationTHE UNIVERSITY OF MANITOBA. DATE: Oct. 22, 2002 Midterm EXAMINATION. PAPER NO.: PAGE NO.: 1of 6 DEPARTMENT & COURSE NO.: 2.277/60.
PAPER NO.: PAGE NO.: 1of 6 GENERAL INSTRUCTIONS You must mark the answer sheet with pencil (not pen). Put your name and enter your student number on the answer sheet. The examination consists of multiple
More informationA MICRO TIME METHOD FOR DETERMINATION OF REDUCING SUGARS, AND ITS APPLICATION TO ANALYSIS OF BLOOD AND URINE.
A MICRO TIME METHOD FOR DETERMINATION OF REDUCING SUGARS, AND ITS APPLICATION TO ANALYSIS OF BLOOD AND URINE. BY JAMES A. HAWKINS. (From Ike Hospital of The Rockefeller Institute for Medical Research,
More informationChapter 2 Part 3: Organic and Inorganic Compounds
Chapter 2 Part 3: Organic and Inorganic Compounds Objectives: 1) List the major groups of inorganic chemicals common in cells. 2) Describe the functions of various types of inorganic chemicals in cells.
More informationTHE DIRECT DETERMINATION OF VALINE AND LEUCINE IN FRESH ANIMAL TISSUES*
THE DIRECT DETERMINATION OF VALINE AND LEUCINE IN FRESH ANIMAL TISSUES* BY B. S. SCHWEIGERT, J. M. McINTIRE, C. A. ELVEHJEM, AND F. M. STRONG (From the Departmerit of Biochemistry, College of Agriculture,
More informationDate: EXERCISE 4. Figure 1. Amino acid structure.
Student s name: Date: Points: Assistant s signature: Index numer: /6 EXERISE 4 AMIN AIDS AND PRTEINS. Amino acids are structural units (monomers) of proteins. There are 20 different amino acids coded for
More informationThe Amino Acid Content of Hen's Egg in Relation to Dietary Protein Intake, Breed and Environment 1
The Amino Acid Content of Hen's Egg in Relation to Dietary Protein Intake, Breed and Environment 1 P. Lunven and C. Le Clément de St. Marcq Protein Food Development Group Nutrition Division In 1963 the
More informationProperties of Proteins
Name Properties of Proteins Experiment #8 Section Pre Lab Exercise 1. Draw the chemical structure for the amino acids glycine, tyrosine, tryptophan, cysteine and methionine. 2. Which of the above amino
More informationChapter 7. Heme proteins Cooperativity Bohr effect
Chapter 7 Heme proteins Cooperativity Bohr effect Hemoglobin is a red blood cell protein that transports oxygen from the lungs to the tissues. Hemoglobin is an allosteric protein that displays cooperativity
More informationThe incorporation of labeled amino acids into lens protein. Abraham Speclor and Jin H. Kinoshita
The incorporation of labeled amino acids into lens protein Abraham Speclor and Jin H. Kinoshita Calf and rabbit lenses cultured in a medium containing a radioactive amino acid incorporate some labeled
More informationTHE ESTIMATION OF PEPSIN, TRYPSIN, PAPAIN, AND CATHEPSIN WITH HEMOGLOBIN
Published Online: 20 September, 1938 Supp Info: http://doi.org/10.1085/jgp.22.1.79 Downloaded from jgp.rupress.org on July 1, 2018 THE ESTIMATION OF PEPSIN, TRYPSIN, PAPAIN, AND CATHEPSIN WITH HEMOGLOBIN
More informationTHE COLORIMETRIC DETERMINATION OF TOTAL PHOSPHOROUS IN PLANT SOLUTIONS.*
THE COLORIMETRIC DETERMINATION OF TOTAL PHOSPHOROUS IN PLANT SOLUTIONS.* R. W. GERDEL.f INTRODUCTION. A review of the literature reveals a number of methods for colorimetric determination of the phosphorous
More informationblue, buffer excretion by titrating back to ph 3*7 with.1 N hydrochloric
CALCIUM CHLORIDE ACIDOSIS. BY J. B. S. HALDANE, R. HILL, AND J. M. LUCK. (From the Biochemical Laboratory, Cambridge.) GYORGY(1) has shown that calcium chloride, when administered to babies, causes an
More informationCHEMICAL AND PHYSICAL CHANGES IN GELATIN SOLUTIONS DURING HYDROLYSIS.
Published Online: 2 March, 1929 Supp Info: http://doi.org/1.185/jgp.12.4.529 Downloaded from jgp.rupress.org on August 26, 218 CHEMICAL AND PHYSICAL CHANGES IN GELATIN SOLUTIONS DURING HYDROLYSIS. BY JOHN
More informationMacromolecules of Life -3 Amino Acids & Proteins
Macromolecules of Life -3 Amino Acids & Proteins Shu-Ping Lin, Ph.D. Institute of Biomedical Engineering E-mail: splin@dragon.nchu.edu.tw Website: http://web.nchu.edu.tw/pweb/users/splin/ Amino Acids Proteins
More informationUSE OF DDGS AS A FEED INGREDIENT ETHANOL AND DDGS OVERVIEW AN EVOLVING ETHANOL INDUSTRY
ETHANOL AND DDGS OVERVIEW 98% of Dried Distillers Grains with Solubles (DDGS) in North America is produced from Ethanol plants for oxygenated fuels 33+ million metric tons of DDGS are produced in North
More informationHUMAN SUBJECT 1. Syracuse, N. Y.) the urine of increasing quantities of these buffers, it has been found in man as in the dog that (1)
THE RENAL REGULATION OF ACID-BASE BALANCE IN MAN. II. FACTORS AFFECTING THE EXCRETION OF TITRATABLE ACID BY THE NORMAL HUMAN SUBJECT 1 By W. A. SCHIESS, J. L. AYER, W. D. LOTSPEICH AND R. F. PITTS WITH
More informationCHAPTER 29 HW: AMINO ACIDS + PROTEINS
CAPTER 29 W: AMI ACIDS + PRTEIS For all problems, consult the table of 20 Amino Acids provided in lecture if an amino acid structure is needed; these will be given on exams. Use natural amino acids (L)
More information(From Washington Square College, New York University.)
6I2.III.22 THE MEASUREMENT OF RED CELL VOLUME. II. Alterations in cell volume in solutions of various tonicities. BY ERIC PONDER AND GEORGE SASLOW. (From Washington Square College, New York University.)
More informationFERTILIZER CONTROL IN 1920
FERTILIZER CONTROL IN 1920 C. O. SWANSON AND W. L. LATSHAW EXPLANATORY STATEMENTS In compliance with the Kansas fertilizer law, samples of the different brands of fertilizer sold the state are each year
More informationDiffusion, osmosis, transport mechanisms 43
Diffusion, osmosis, transport mechanisms 43 DIFFUSION, OSMOSIS AND TRANSPORT MECHANISMS The cell membrane is a biological membrane that separates the interior of all cells from the outside environment
More informationCHEMISTRY OF LIFE 05 FEBRUARY 2014
CHEMISTRY OF LIFE 05 FEBRUARY 2014 In this lesson we will: Lesson Description Discuss inorganic compounds and their importance Discuss organic compounds and their biological importance. Summary Inorganic
More informationIonization of amino acids
Amino Acids 20 common amino acids there are others found naturally but much less frequently Common structure for amino acid COOH, -NH 2, H and R functional groups all attached to the a carbon Ionization
More informationELEMENTS OF PSYCHOPHYSICS Sections VII and XVI. Gustav Theodor Fechner (1860/1912)
ELEMENTS OF PSYCHOPHYSICS Sections VII and XVI Gustav Theodor Fechner (1860/1912) Translated by Herbert Sidney Langfeld (1912) [Classics Editor's note: This translation of these passages from Fechner's
More informationSupplying Nutrients to Crops
Supplying Nutrients to Crops What is Plant Nutrition? Plants need nutrients for healthy growth and development. Plant nutrition involves the absorption of nutrients for plant growth and is dependent on
More informationDraft Indian Standard SODIUM HYDROXIDE, FOOD GRADE SPECIFICATION
Doc:FAD 8(1886)C Draft Indian Standard SODIUM HYDROXIDE, FOOD GRADE SPECIFICATION Not to be reproduced without the permission of BIS or used as a Standard Last date for receipt of comments is 2008 05 15
More informationTHE INFLUENCE OF TEMPERATURE ON HEMOLYSIS IN HYPOTONIC SOLUTIONS.'
THE INFLUENCE OF TEMPERATURE ON HEMOLYSIS IN HYPOTONIC SOLUTIONS.' BY PAUL A. LEWIS, M.D. (From the Antitoxin Laboratory of the Massachusetts State Board of Health.) During the year I905-I906 it was my
More informationDISTRIBUTION OF NON-SUGARS IN THE ARI COUPLED LOOP MOLASSES DESUGARIZATION SYSTEM
DISTRIBUTION OF NON-SUGARS IN THE ARI COUPLED LOOP MOLASSES DESUGARIZATION SYSTEM D. E. Rearick*, Cheri McKay and Alla Bagramyan Amalgamated Research LLC, P.O. Box 228, Twin Falls, ID 83303 I. Introduction
More informationRADIOACTIVE PHOSPHORUS AS AN INDICATOR OF PHOSPHOLIPID METABOLISM
RADIOACTIVE PHOSPHORUS AS AN INDICATOR OF PHOSPHOLIPID METABOLISM XI. THE INFLUENCE OF METHIONINE, CYSTINE, AND CYSTEINE UPON THE PHOSPHOLIPID TURNOVER IN THE LIVER* BY I. PERLMAN, N. STILLMAN, AND I.
More informationCHEMICAL STUDIES ON BACTERIAL AGGLUTINATION II. THE IDENTITY OF PRECIPITIN AND AGGLUTININ* BY MICHAEL HEIDELBERGER, PH.D., AND ELVIN A.
CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION II. THE IDENTITY OF PRECIPITIN AND AGGLUTININ* BY MICHAEL HEIDELBERGER, PH.D., AND ELVIN A. KABAT (From the Laboratories of the Departments of Medicine and Biological
More informationBY FRANCIS P. CHINARD WITH THE TECHNICAL ASSISTANCE OF DORA M. NEWELL. (Received for publication, July 28, 1948)
USE OF THE HYPOBROMITE REACTION FOR THE ESTIMATION OF AMMONIA PLUS UREA NITROGEN IN URINES CON- TAINING LARGE AMOUNTS OF PROTEIN; THE REAC- TION OF ALKALINE HYPOBROMITE WITH PROTEINS BY FRANCIS P. CHINARD
More informationTowards a New Paradigm in Scientific Notation Patterns of Periodicity among Proteinogenic Amino Acids [Abridged Version]
Earth/matriX: SCIENCE TODAY Towards a New Paradigm in Scientific Notation Patterns of Periodicity among Proteinogenic Amino Acids [Abridged Version] By Charles William Johnson Earth/matriX Editions P.O.
More information