Complementary molecular shapes and additivity of the packing
|
|
- Dina Houston
- 6 years ago
- Views:
Transcription
1 Proc. Natl. Acad. Sci. USA VO1. 88, pp , January 1991 Biophysics Complementary molecular shapes and additivity of the packing parameter of lipids (chain length/phase preference/theory) V. V. KUMAR The Hormel Institute, University of Minnesota, th Avenue NE, Austin, MN Communicated by Ralph T. Holman, October 15, 1990 (received for review March 19, 1990) ABSTRACT Physical dimensions of a membrane component influence its phase preference upon hydration. A dimensionless packing parameter, S, given by S = V/al, where V is the hydrocarbon volume, a is the area of the head group, and I is the critical length of the hydrocarbon chain, is useful in determining the phase preference of a lipid, and the value of S usually lies between 0.5 and 1 for bilayers. Here, the value of S is calculated for phosphatidylcholine (PC) and lysophosphatidylcholine (lysopc) as a function of chain length, and it is shown that diacylpc having an S value of <0.74 does not form bilayers. For example, diacylpc, up to a chain length of eight carbon atoms, forms only micelles, whereas higher homologs with S > 0.74 form bilayers. It is also shown that when lipid molecules having complementary shapes associate, the value of S becomes additive. Using the additivity of S, a number of experimental results for lipid mixtures can be explained. For example, lysopc and cholesterol form lamellar structures between 45 and "40 mol% cholesterol, and the additive value of S for this region is between 0.74 and 1. Similarly, the additivity of S shows that the maximum amount of cholesterol that can be incorporated into PC bilayers is 50 mol%, in agreement with experimental studies. Molecular shape is an important consideration in membrane modeling. Based on the physical dimensions of a membrane component, its phase presence upon hydration and its location in the membrane can often be predicted. Taking into account interaction free energies, molecular geometry, and entropy, theoreticians have developed a dimensionless packing parameter, S, that is useful in determining the size and shape of lipid aggregates. S is given by S = V/al, where V is the hydrocarbon volume, a is the area of head group, and 1 is the critical length of the hydrocarbon chain (1-3). a, V, and I are all estimable or measurable (4), and the value of S can be calculated. The value of S determines the aggregate formed by lipids or any amphiphiles upon hydration. It has been shown that lipids aggregate to form spherical micelles (S < 1/3), nonspherical (cylindrical) micelles (1/3 < S < 1/2), bilayers (1/2 < S < 1), and reverse micelles or hexagonal (HI,) phases (S > 1). However, theoreticians caution that the above predicted limits set on the values of S are relatively insensitive to the exact values of V and a but are strongly dependent upon the choice of 1 (5). The packing parameter S has successfully predicted that single-chain lipids like lysophosphatidylcholine (lysopc) (S = 1/3 to 1/2) having an inverted cone or wedge shape form micelles, double-chain lipids with large head group areas and fluid chains like phosphatidylcholines (PCs) (S = 1/2 to 1) having a cylindrical shape form bilayers, and, finally, cholesterol (Chol) and some double-chain lipids with small head group areas like unsaturated phosphatidylethanolamines The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C solely to indicate this fact. (PEs) (S > 1) having a truncated cone shape adopt hexagonal HI, phases upon hydration (1-3). Cylindrical and wedge-shaped molecules have been shown to be essential for spontaneous vesiculation (6) as well as bilayer stabilization (7, 8). It has also been shown experimentally that molecules having complementary molecular shapes can form bilayer structures. Inverted cone (wedge)- shaped lysopc and cone-shaped Chol or unsaturated PE can interact stoichiometrically to form bilayer structures (9-12). lysopc and fatty acids in equimolar proportion were shown to form bilayer structures and, in this case, fatty acid complexes with lysopc to produce PC-type molecules (13). In all of the above examples, the resulting complexes were assumed to be cylindrical in shape, leading to bilayerformation. Although it is not explicitly shown above, it is implied that the value of S is additive in producing a cylindrical complex from a mixture of cone-shaped and inverted cone-shaped molecules. The present paper supports the hypothesis of the additivity of S values when two or more lipids of different shapes are present in a model system. It was concluded that the additivity rule applies, and from this a number of experimental observations can be explained. The additivity of S values was tested on a number of binary and ternary lipid systems, and the results of these calculations and their implications on experimental results are presented. RESULTS Selection of a, V, and I for a given lipid is of paramount importance in the calculations presented. The head group area chosen was 71.7 A2 for PC and lysopc, 42 A2 for PE, and 19 A2 for Chol (5, 14). The value selected for PC is in agreement with the 71 A2 value determined for PCs with saturated acyl chains (14). The hydrocarbon volume and the length chosen for Chol are 400 A3 and A, respectively (5). Correct estimation of V for a series of PCs can be obtained from densities and partial specific volumes. Nagle and Wilkinson (15), Laggner and Stabinger (16), and Melchoir et al. (17) measured the densities and partial specific volumes for a number of PCs, and Knoll (18) measured the values for deuterated PCs. Small (19) used the dilatometric data of Nagle and Wilkinson (15) to calculate the molecular volumes of PCs as a function of chain length for the L<, and Ph phases and also at a constant temperature of 55 C. The molecular volumes were generally lower in the gel state and at 55 C than those in the liquid crystalline state, and no appreciable differences in the volumes were detected between sonicated and unsonicated forms of PCs (19). The volume per -CH2 Abbreviations: PC, phosphatidylcholine; lysopc, lysophosphatidylcholine; PE, phosphatidylethanolamine; Chol, cholesterol; S, packing parameter; V, volume of hydrocarbon chain; a, area of head group; 1, length of hydrocarbon chain; cmc, critical micelle concentration. 444
2 Biophysics: Kumar group calculated ranged from 27 A3 at 550C and also in the P~ state to 30.9 A3 in the La state. The volume of 27 A3 per -CH2 group at 550C is very low compared to the volume in alkanes, fatty alcohols, and fatty acids in the liquid state. Small (19) indicated that at 550C all of the lipids are in a single phase with an extra degree offreedom in the system. Short-chain PCs are more expanded than long-chain PCs, giving a low increase in volume for each -CH2 group increment. However, at the phase transition temperature, this additional degree of freedom is eliminated (19). It is therefore reasonable to assume a value of 30.9 A3 per -CH2 group, and using this value the hydrocarbon volumes for PCs as a function of chain length are calculated. The S values calculated using this value of molecular volume explain a number of experimental observations (see Discussion). The value of I is calculated using the equation I = n', where n' is the number of carbon atoms of the hydrocarbon chain that are embedded in the hydrocarbon core and is usually less than nc, the total number of carbon atoms in the hydrocarbon chain (4). The value of 1 is 80% of the fully extended chain length. Hence, the S values reported are calculated using 80% of the extended chain length. As discussed above, V and I can be calculated for PC and lysopc with different hydrocarbon chain lengths. These values of Vand 1, along with the values ofa mentioned earlier, are utilized to calculate S for PC and lysopc as a function of chain length. In Fig. 1, S is plotted as a function of chain length for PC and lysopc having saturated acyl chains. It can be seen from Fig. 1 that the S value increases rapidly for both PC and lysopc having short chain lengths, whereas it remains practically constant for lipids with long chain lengths. For PC, the value of S remains constant from about 10 carbon atoms in each of the fatty acyl chains. Experimental evidence indicates that PC molecules having 8 or less carbon atoms in each of the acyl chains form only micelles (20, 21), whereas higher homologs form bilayer structures (22). Extrapolation of the straight-line region of the curve for PC in Fig. 1 (circles) from a carbon chain length of 10 to S results in an S value of Therefore, the value of S for diacytpc should be for bilayer structures to form. For lysopc, the value ofs remains constant from about 8 carbon atoms (see Fig. 1, squares). Here, also, experimental evidence indicates that lysopc molecules with 8 or more carbon atoms in the fatty acyl chain form micelles, whereas lower homologs do not because of their very high critical micelle concentration (cmc) values Proc. Natl. Acad. Sci. USA 88 (1991) 445 (V.V.K. and W. J. Baumann, unpublished observations). Extrapolation of the straight-line region of the curve for lysopc in Fig. 1 (squares) from a carbon length of 8 to S gives an S value of0.34. Therefore, the value ofs for lysopc should be.0.34 for micelle formation. In fact, the value of S for C4- and C2-lysoPC lies below 0.34, indicating that these lysophospholipids do not form micelles. It is our experience that C6-lysoPC did not form micelles even at very high concentrations (-0.7 M) (V.V.K. and W. J. Baumann, unpublished observations). In this case, the solubility limit of the lipid precedes the cmc and, hence, no micelle formation occurs. The results presented in Fig. 1 indicate that an S value is necessary for micelle formation by saturated lysopc, whereas an S value.0.74 is essential for bilayer formation by saturated diacylpcs. A critical test for the limits proposed for S values is to calculate the values of S for different lipid mixtures and compare the bilayer limits set by the value of S with experimentally known bilayer limits. For example, in a PC/Chol system the two lipids form bilayer structures only up to 50 mol% Chol (23). Similarly, lysopc and Chol form bilayer structures only when the mol% of Chol is between 45 and 80 (11, 24, 25). In Fig. 2, the value of S is plotted for C16-lysoPC and dicj6pc as a function of mol% Chol. S values are calculated assuming the additivity of S. For example, at 50 mol% Chol in a C16-lysoPC/Chol system the value of S would be [0.5 x (S value for lysopc)] + [0.5 x 1.21 (S value for Chol)] = Similarly, S is calculated for other lysopc/chol and dic16pc/chol mixtures. It can be seen from Fig. 2 that for the dic16pc/chol system, the value of S begins at at 0 mol% Chol and reaches 1 at 50 mol% Chol. It was shown that dic16pc and Chol form lamellar structures up to 50 mol% Chol and any excess Chol forms a separate crystalline Chol phase (23). The theoretical value of S presented in Fig. 2 as well as the experimental evidence indicates that dic16pc/chol mixtures remain in the bilayer state up to 50 mol% Chol. Finally, Chol is known to exhibit a "condensing effect" in saturated PC/Chol systems. This condensing would have little or no effect on the calculations presented here, and an excellent theoretical analysis of this was reported earlier (26). It is also shown in Fig. 2 that the value of S increases linearly with increasing mol% Chol for the C16-lysoPC/Chol system. The value ofs remains in the lamellar phase between 45 and =80 mol% Chol. It was observed by freeze-fracture electron microscopy (27) and x-ray diffraction (25) that lysopc/chol mixtures form lamellar structures with F F 0.4 F F LE-31 E3 LE-3 w Chain length FIG. 1. Changes in calculated S values as a function of chain length for PC (o) and IysoPC (o) mol% Chol FIG. 2. S values for PC (o) and lysopc (o) as a function of mol% Chol. S value for mixtures is calculated as described in Results.
3 446 Biophysics: Kumar mol% Chol. NMR spectroscopic evidence indicates that lysopc and Chol in equimolar proportion, as well as up to 60 mol% Chol, upon sonication form stable vesicles (9, 10, 28). Thus, the theoretical values of S as well as the experimental data support the fact that C16-lysoPC/Chol produces bilayer structures only when Chol is present at mol%. In Fig. 3, changes in the additive S are plotted for PC/PE (circles) and lysopc/pe (squares) systems with increasing mol% of PE. It is shown in Fig. 3 that the lysopc/pe mixture remains in the bilayer state from 35 to 60 mol% PE. It was shown by 31P NMR that lysopc and PE form bilayer structures up to 50 mol% PE due to their complementary molecular shapes (12). In a similar fashion, it was shown by 31p NMR that PE and PC remain in the bilayer state up to 50 mol% PE (29). The results shown in Fig. 3 (circles) are in agreement with these experimental results. In Fig. 4, changes in the S values for the dic16pc/c16- lysopc system as a function of lysopc mol% are presented. It is shown in Fig. 4 that the value of S falls below 0.74 when the mol% of lysopc is between 15 and 20, indicating that dic16pc and lysopc do not form stable lamellar structures when the mol% of lysopc exceeds 20. It was shown experimentally that the maximum amount of lysopc that can be incorporated into dic16pc small unilamellar vesicles (SUV) without the loss of ionic permeability barrier is about 21.8 mol% (30). Similarly, the amount of lysopc that was shown to be incorporated into dic16pc multilamellar vesicles (MLV) was 30 mol% (11). Although there is some variation between the theoretical predictions and the experimental observations, it should be noted that the amount of lysopc that can be incorporated into PC vesicles (both MLV and SUV) varies over a considerable range depending upon the nature of PC and lysopc (31). The S value calculated for the system dic6pc and C6-lysoPC as a function of mol% of C6-lysoPC always lies below 0.74, indicating that these two lipids (in any proportion) do not form bilayers. 31P NMR spectroscopy and freeze-fracture electron microscopy failed to reveal the presence of lamellar structures in these mixtures (V.V.K. and W. J. Baumann, unpublished observations). Similarly, the additive packing parameter for the system dic6pc/c16- lysopc is always below 0.74, indicating that these two lipids in any proportion do not form bilayers. 31P NMR spectroscopy and freeze-fracture electron microscopy showed the presence of micellar structures, consistent with the predictions presented here. The additive S value for a 3:1 dicj6pc/ lysopc mixture in which the chain length of lysopc varied increases as the chain length of lysopc increases and finally [ Proc. Natl. Acad. Sci. USA 88 (1991) I I- u mol% lysopc FIG. 4. S value for dic16pc/c16-lysopc as a function of mol% C16-lysoPC. reaches a value between 0.75 and 0.8 when the chain length of lysopc is 16 (data not shown). From past experience, dic16pc formed stable bilayers only when the chain length of lysopc was 14 or higher (30). The slight disagreement between the experimental values and theoretical predictions in all of the examples discussed above could be due to the simplicity in calculating S. A more rigorous treatment of the additivity data, taking into account the effect of curvature, might result in a better agreement. Finally, it should be appreciated that simple additivity leads to a better understanding of which lipid mixtures form bilayers. Having established the validity of limits proposed for S for binary lipid mixtures, these limits were applied to ternary lipid mixtures. In Fig. 5 the changes in S for the ternary system of PC/lysoPC/Chol are presented. The mol% of PC decreased from 100 to 0 from left to right with increasing the mol fraction oflysopc and Chol in equimolar proportion (Fig. 5, circles). A similar explanation can be given for ternary systems in which Chol (Fig. 5, triangles) and lysopc (Fig. 5, squares) mol% decreased from 100 to 0 from left to right. Considering the PC system containing various mol fractions '5 -o io mol% PE FIG. 3. S values for PC/PE (o) and lysopc/pe (o) systems as a function of mol% PE. A1 _0 I. A I mol fraction 1.0 FIG. 5. S value for the ternary system containing PC, lysopc, and Chol. o, The mol% of PC decreases from 100 to 0 from left to right. The mol fraction of lysopc and Chol increases from left to right in equimolar proportion. o, lysopc/pc/chol system. A, Chol/PC/ lysopc system.
4 Biophysics: Kumar of lysopc and Chol (Fig. 5, circles), the value of S is always -0.8, which indicates that the system remains in the bilayer state irrespective of the mol fraction of lysopc and Chol as long as lysopc and Chol are in equimolar proportion. 31P NMR spectroscopy and barrier property measurements were utilized to show that PC remains in the bilayer state when equimolar proportions of lysopc and Chol are present in the system (11, 26, 32). For the lysopc system containing equimolar amounts of PC and Chol (Fig. 5, squares), the value of S remains below 0.74 until the mol% of lysopc reaches 40. The system then remains in the bilayer state even with no lysopc but with equimolar PC and Chol. The same resulti.e., PC and Chol up to 50 mol% Chol form bilayer structures-was also observed in Fig. 2. DISCUSSION The results presented in Figs. 1-5 indicate two important phenomena: (i) that the value of S should be for bilayer formation by saturated diacylpcs and (ii) that S is additive when lipid mixtures are present. The results presented in Fig. 1 indicate that a minimum S value of 0.74 is necessary for diacylpcs to form bilayer structures. Such an S value is possible only for diacylpcs having 10 or more carbon atoms in each of the fatty acyl chains. Experimental evidence is strongly supportive, as it has been shown that saturated diacylpcs having 8 or less carbon atoms in each of the fatty acyl chains form only micelles, whereas higher homologs form bilayers (20-22). It is interesting to point out that a similar phenomenon was observed for diacylpcs in the plots of changes in transition temperature (ATm), enthalpy (AH), entropy (AS), and volume (AV) as a function of chain length. In these plots the values of ATm, AH, AS, and AV increase more steeply for lower homologs compared to higher homologs, and extrapolation of these curves to zero Al and zero AS resulted in a chain length of 11 carbon atoms (19). Also, a transition temperature of -8.5 C was recorded for dicj0pc (33), and no data are available for dic8pc showing a chain transition. These findings indicate that a minimum of 10 carbon atoms in each of the fatty acyl chains are necessary for bilayer formation, and a similar conclusion can be drawn from the S value versus the chain length curve shown in Fig. 1. Thus, S values, changes in ATm, AH, AS, and AV, as well as experimental evidence, indicate that bilayer formation for diacylpcs is possible only when 10 or more carbon atoms are present in each of the acyl chains. The results presented in Fig. 1 (squares) also indicate that the value of S should be for lysopc to form micelles. Such an S value is possible only for lysopcs with 8 or more carbon atoms in the fatty acyl chain. Experimental evidence is strongly supportive in that C6-lysoPC and lower homologs do not form micelles because their cmc values are very high and the solubility limit of the lipid precedes the cmc (V.V.K. and W. J. Baumann, unpublished observations). It was shown earlier that C16-, C18-, and C20-lysoPC form interdigitated bilayer structures at temperatures below their bilayermicellar transition temperature (11, 34). However, the results presented in Fig. 1 (squares) indicate that these lysopcs form only micelles. This is due to the fact that the hydrocarbon volumes and, hence, S values are calculated above the transition temperature. The additive S value for dic16pc/chol mixtures, shown in Fig. 2, lies below 1 up to equimolar amounts of Chol. Experimental evidence also indicates that PC/Chol mixtures remain in the bilayer state up to 50 mol% Chol and excess Chol forms a separate crystalline phase (23). Also shown in Fig. 2 (squares) is that the additive S for lysopc/chol reaches 0.74 when the mol% of Chol is 45 and remains in the bilayer state up to -80 mol% Chol. There is ample evidence in the Proc. Natl. Acad. Sci. USA 88 (1991) 447 literature to indicate that lysopc and Chol form lamellar structures in equimolar proportions. Dervichian (35) first observed that "lysolecithin associated with cholesterol in equimolar proportions swells and gives myelinic figures as does lecithin alone." It was observed by freeze-fracture electron microscopy (27) and x-ray diffraction (25) that lysopc forms lamellar structures with mol% Chol. The formation of lamellar structures by equimolar lysopc and Chol was confirmed by differential scanning calorimetry (24), x-ray diffraction (25) and barrier property measurements (11, 32), and NMR spectroscopy (9, 10, 28). Experimental data and theoretical predictions are in agreement with each other in regard to the amount of Chol necessary for bilayer formation by lysopc. In a similar fashion, the phase adopted by PC/PE, lysopc/pe, dic16pc/c16-lysopc systems (Figs. 3 and 4) assuming additivity are in agreement with experimental r'sults as discussed earlier. A very important and interesting phenomena that emerged from the additivity of packing parameter values for lipid mixtures is a plausible model in better understanding lysopc/ Chol antagonism. The results presented in Fig. 5 clearly indicate that PC remains in the bilayer phase provided lysopc and Chol are in equimolar proportion. When lysopc is incorporated into PC bilayers it induces structural changes. These changes usually result in increased membrane permeability (36), cause membrane fusion (37), and eventually lead to lamellar disruption (38). In contrast, Chol in phospholipid lamellae behaves as if it were a truncated cone (5), and its incorporation into PC bilayers reduces membrane permeability, broadens the gel to liquid-crystalline phase transition, and decreases average molecular surface areas (39-42). It is not only that lysopc and Chol affect phospholipid bilayers quite differently, but when both are present in similar proportions, they appear to counteract each other's effect (11, 24, 32, 43). Although such a large body of experimental evidence exists for lysopc/chol antagonism, results presented in Fig. 5 offer a likely model for understanding lysopc/chol antagonism. In conclusion, the calculations shown in this paper establish that the value of S is additive when lipids with complementary molecular shapes associate to form bilayer structures, and these bilayer structures form only when the values of S lie between 0.74 and 1. The agreement between the calculated S values for the lipid mixtures to form bilayers and the experimental data is quite surprising given the simplicity of S. The results presented in this paper show that S is additive, although it was recently suggested that it is difficult to see how V/al can be applied to lipid mixtures (44). It should be noted that in addition to the Israelachvili (1-3) model to explain the phase behavior of hydrated lipids, another interesting theory called intrinsic radius of curvature was also advocated to explain the presence of bilayer and nonbilayer lipids in biological membranes (45, 46). However, it was recently suggested that the determination of intrinsic radius of curvature of bilayer lipids is not always possible (47). Bilayer structure of membranes is the most popular, and membrane permeability is the only major, functional role of lipids which may be regarded as firmly established. If so, a simple unsaturated PC species would easily satisfy such a demand. However, a simple biomembrane such as that of erythrocytes contains well over 100 different lipid species with diverse molecular shapes. In essence, membrane integrity is maintained by a delicate balance of lipids of different shapes. These different shapes may complement each other and maintain a bilayer structure although neither of two components can form bilayers by itself (Fig. 5). The additivity of S proposed here should be useful in predicting which membrane components complement their shapes and form (or maintain) bilayer structures.
5 448 Biophysics: Kumar I acknowledge the helpful discussions and encouragement of Drs. W. J. Baumann and B. Malewicz and the assistance of Kim Kestner with the drawings and Julie Knutson with the typing. This research was supported by National Institutes of Health Program Project Grant HL08214 from the National Heart, Lung and Blood Institute and by the Hormel Foundation. 1. Israelachvili, J. N., Mitchell, D. J. & Ninham, B. W. (1976) J. Chem. Soc. Faraday Trans. 2 72, Israelachvili, J. N., Marcelja, S. & Horn, R. G. (1980) Q. Rev. Biophys. 13, Israelachvili, J. N. (1985) Intermolecular and Surface Forces (Academic, New York), pp Tanford, C. (1980) The Hydrophobic Effect: Formation of Micelles and Biological Membranes (Wiley, New York), pp Carnie, S., Israelachvili, J. N. & Pailthorpe, B. A. (1979) Biochim. Biophys. Acta 554, Hauser, H. (1989) Proc. Natl. Acad. Sci. USA 86, Kumar, V. V., Malewicz, B. & Baumann, W. J. (1989) Biophys. J. 55, Lasch, J., Hoffman, J., Omelynenko, W. G., Klibanov, A. A., Torchilin, V. P., Binder, H. & Gawrisch, K. (1990) Biochim. Biophys. Acta 1022, Kumar, V. V. & Baumann, W. J. (1986) Biochem. Biophys. Res. Commun. 139, Kumar, V. V., Anderson, W. H., Thompson, E. W., Malewicz, B. & Baumann, W. J. (1988) Biochemistry 27, van Echteld, C. J. A., de Kruijff, B., Mandersloot, J. G. & de Gier, J. (1981) Biochim. Biophys. Acta 649, Madden, T. D. & Cullis, P. R. (1982) Biochim. Biophys. Acta 684, Jain, M. K., van Echteld, C. J. A., Ramirez, F., de Gier, J., de Haas, G. H. & van Deenen, L. L. M. (1980) Nature (London) 284, Rand, R. P. & Parsegian, V. A. (1989) Biochim. Biophys. Acta 988, Nagle, J. F. & Wilkinson, D. A. (1978) Biophys. J. 23, Laggner, P. & Stabinger, H. (1976) in Proceedings of the 50th International Conference on Colloid and Interface Science, ed. Kerker M. (Academic, New York), pp Melchoir, D. L., Scavitto, F. J. & Steim, J. M. (1980) Biochemistry 19, Knoll, W. (1981) Chem. Phys. Lipids 28, Small, D. M. (1986) The Physical Chemistry oflipids (Plenum, New York), pp Tausk, R. J. M., Karmiggelt, J., Oudshoorn, C. & Overbeek, J. Th. G. (1974) Biophys. Chem. 1, Proc. Natl. Acad. Sci. USA 88 (1991) 21. Burns, R. A. & Roberts, M. F. (1980) Biochemistry 19, Racey, T. J., Singer, M. A., Finegold, L. & Rochon, P. (1989) Chem. Phys. Lipids 49, de Kruijff, B., Cullis, P. R. & Radda, G. K. (1976) Biochim. Biophys. Acta 436, Klopfenstein, W. E., de Kruyff, B., Verkleij, A. J., Demel, R. A. & van Deenen, L. L. M. (1974) Chem. Phys. Lipids 13, Rand, R. P., Pangborn, W. A., Purdon, A. D. & Tinker, D. 0. (1975) Can. J. Biochem. 53, Israelachvili, J. N. & Mitchell, D. J. (1975) Biochim. Biophys. Acta 389, Purdon, A. D., Hsia, J. C., Pinteric, L., Tinker, D. O. & Rand, R. P. (1975) Can. J. Biochem. 53, Ramsammy, L. S. & Brockerhoff, H. (1982) J. Biol. Chem. 257, Cullis, P. R. & de Kruijff, B. (1978) Biochim. Biophys. Acta 507, Lee, Y. & Chan, S. I. (1977) Biochemistry 16, Ralston, E., Blumenthal, R., Wienstein, J. N., Sharrow, S. D. & Henkart, P. (1980) Biochim. Biophys. Acta 597, Kitagawa, T., Inoue, K. & Nojima, S. (1976) J. Biochem. (Tokyo) 79, Huang, C., Lapides, J. R. & Levin, I. W. (1982) J. Am. Chem. Soc. 104, Wu, W., Huang, C., Coneley, T. G., Martin, R. B. & Levin, I. W. (1982) Biochemistry 21, Dervichian, D. G. (1946) Trans. Faraday Soc. 42B, Morris, D. A. N., McNeil, R., Castellino, F. J. & Thomas, J. K. (1980) Biochim. Biophys. Acta 599, Elamrani, K. & Blume, A. (1982) Biochemistry 21, Bangham, A. D. & Horne, R. W. (1964) J. Mol. Biol. 8, de Bernard, L. (1958) Bull. Soc. Chim. Biol. 40, Demel, R. A., van Deenen, L. L. M. & Pethica, B. A. (1967) Biochim. Biophys. Acta 135, Bittman, R., Clejan, S., Jain, M. K., Deroo, P. W. & Rosenthal, A. F. (1981) Biochemistry 20, Murari, R., Murari, M. P. & Baumann, W. J. (1986) Biochemistry 25, Inoue, K. & Kitagawa, T. (1974) Biochim. Biophys. Acta 363, Gruner, S. M. (1989) J. Phys. Chem. 93, Gruner, S. M. (1985) Proc. Natl. Acad. Sci. USA 82, Tate, M. W. & Gruner, S. M. (1987) Biochemistry 26, Hui, S. W. & Sen, A. (1989) Proc. Natl. Acad. Sci. USA 86,
EFFECTS OF CHOLESTEROL ON THE PROPERTIES OF EQUIMOLAR MIXTURES OF SYNTHETIC PHOSPHATIDYLETHANOLAMINE AND PHOSPHATIDYLCHOLINE
21 Biochimica et Biophysica Acta, 513 (1978) 21--30 Elsevier/North-Holland Biomedical Press BBA 78160 EFFECTS OF CHOLESTEROL ON THE PROPERTIES OF EQUIMOLAR MIXTURES OF SYNTHETIC PHOSPHATIDYLETHANOLAMINE
More informationX-ray diffraction study on interdigitated structure of phosphatidylcholines in glycerol
X-ray diffraction study on interdigitated structure of phosphatidylcholines in glycerol Hiroshi Takahashi 1,*, Noboru Ohta 2 and Ichiro Hatta 2 1 Department of Physics, Gunma University, 4-2 Aramaki, Maebashi
More informationLIPID POLYMORPHISM AND THE ROLES OF LIPIDS IN MEMBRANES
Chemistry and Physics of Lipids, 40 (1986) 127-144 127 Elsevier Scientific Publishers Ireland Ltd. LIPID POLYMORPHISM AND THE ROLES OF LIPIDS IN MEMBRANES PIETER R. CULLIS, MICHAEL J. HOPE and COLIN P.S.
More informationBiology 5357: Membranes
s 5357 Biology 5357: s Assembly and Thermodynamics of Soft Matter Paul H. MD, PhD Department of Cell Biology and Physiology pschlesinger@.wustl.edu 362-2223 Characteristics s 5357 s are polymorphic s 5357
More informationEffect of Lipid Characteristics on the Structure of Transmembrane Proteins
141 Biophysical Journal Volume 75 September 1998 141 1414 Effect of Lipid Characteristics on the Structure of Transmembrane Proteins N. Dan* and S. A. Safran *Department of Chemical Engineering, University
More informationVol. 110, No. 1, 1983 January 14, 1983
January 14, 1983 Pages 15-22 Ca 2+ AND_ ph INDUCED FUSION OF SMALL UN!L~ELL#~ VESICLES CONSISTING OF PHOSPHATIDYLETHANOLAMINE AND NEGATIVELY CHARGED PHOSPHOLIPIDS: A FREEZE FRACTURE STUDY (a) (b) M.J.
More informationPROCEEDINGS OF THE YEREVAN STATE UNIVERSITY
PROCEEDINGS OF THE YEREVAN STATE UNIVERSITY Physical and Mathematical Sciences 2018, 52(3), p. 217 221 P h y s i c s STUDY OF THE SWELLING OF THE PHOSPHOLIPID BILAYER, DEPENDING ON THE ANGLE BETWEEN THE
More informationRETINOID-PHOSPHOLIPID INTERACTIONS AS STUDIED BY MAGNETIC RESONANCE. Stephen R. Wassail* and William Stillwellt
Vol.''% No. 3 85 RETINOID-PHOSPHOLIPID INTERACTIONS AS STUDIED BY MAGNETIC RESONANCE Stephen R. Wassail* and William Stillwellt Departments of Physics* and Biology+ Indiana University-Purdue University
More informationSelf-Assembly. Lecture 3 Lecture 3 Surfactants Self-Assembly
Self-Assembly Lecture 3 Lecture 3 Surfactants Self-Assembly Anionic surfactants unsaturated omega-3 3 fatty acids rd carbon from the metyl end has double bond saturated Non-ionic surfactants Cationic surfactants
More informationSpontaneous vesicle formation by mixed surfactants
Progress in Colloid & Polymer Science Progr Colloid Polym Sci 84:3--7 (1991) Spontaneous vesicle formation by mixed surfactants S. A. Safranl'4), E C. MacKintosh1), P. A. Pincus2), and D. A. Andelman 3)
More informationphosphatidylethanolamine/water model membrane system
Effect of bile salts on monolayer curvature of a phosphatidylethanolamine/water model membrane system Robin L. Thurmond, Goran Lindblom, and Michael F. Brown Department of Chemistry, University of Arizona,
More informationChapter 1 Membrane Structure and Function
Chapter 1 Membrane Structure and Function Architecture of Membranes Subcellular fractionation techniques can partially separate and purify several important biological membranes, including the plasma and
More informationBarotropic Phase Transitions of Dilauroylphosphatidylcholine Bilayer Membrane
High Pressure Bioscience and Biotechnology 68 Proceedings of the 4 th International Conference on High Pressure Bioscience and Biotechnology, Vol. 1, 68 72, 2007 Barotropic Phase Transitions of Dilauroylphosphatidylcholine
More informationPhysical Cell Biology Lecture 10: membranes elasticity and geometry. Hydrophobicity as an entropic effect
Physical Cell Biology Lecture 10: membranes elasticity and geometry Phillips: Chapter 5, Chapter 11 and Pollard Chapter 13 Hydrophobicity as an entropic effect 1 Self-Assembly of Lipid Structures Lipid
More informationIntrinsic curvature hypothesis for biomembrane lipid composition: A role for nonbilayer lipids (Ha phase/lipid phase transltions/phospholipid)
Proc. Nail. Acad. Sci. USA Vol. 82, pp. 3665-3669, June 1985 Biophysics Intrinsic curvature hypothesis for biomembrane lipid composition: A role for nonbilayer lipids (Ha phase/lipid phase transltions/phospholipid)
More informationDue in class on Thursday Sept. 8 th
Problem Set #1 Chem 391 Due in class on Thursday Sept. 8 th Name Solutions 1. For the following processes, identify whether G, H and S are positive (+), negative (-) or about zero (~0) at the standard
More informationStudy of the Emulsion Stability and Headgroup Motion of
Agric. Biol. Chem., 53 (4), 995-1001, 1989 995 Study of the Emulsion Stability and Headgroup Motion of Phosphatidylcholine Kazuhiro and Lysophosphatidylcholine by 13C- and 31P-NMR Chiba and Masahiro Tada
More informationChapter 12: Membranes. Voet & Voet: Pages
Chapter 12: Membranes Voet & Voet: Pages 390-415 Slide 1 Membranes Essential components of all living cells (define boundry of cells) exclude toxic ions and compounds; accumulation of nutrients energy
More information0.5 nm nm acyl tail region (hydrophobic) 1.5 nm. Hydrophobic repulsion organizes amphiphilic molecules: These scales are 5 10xk B T:
Lecture 31: Biomembranes: The hydrophobic energy scale and membrane behavior 31.1 Reading for Lectures 30-32: PKT Chapter 11 (skip Ch. 10) Upshot of last lecture: Generic membrane lipid: Can be cylindrical
More information68 3. Membrane Models and Model Membranes I. MEMBRANE STRUCTURE
68 3. Membrane Models and Model Membranes branes separating two aqeous phases: Formation of a membrane of a single composition," J. Mol. Biol. 8 (1964): 148-160. 38. Ghosh, D., M. A. Williams, and J. Tinoco,
More informationChemistry and Physics of LipMs, 35 (1984) Elsevier Scientific Publishers Ireland Ltd.
Chemistry and Physics of LipMs, 35 (1984) 363-370 363 Elsevier Scientific Publishers Ireland Ltd. INFLUENCE OF CHOLESTEROL ESTERS OF VARYING UNSATURATION ON THE POLYMORPHIC PHASE PREFERENCES OF EGG PHOSPHATIDYLETHANOLAMINE
More informationPhysical effects underlying the transition from primitive to modern cell membranes
Physical effects underlying the transition from primitive to modern cell membranes Itay Budin and Jack W. Szostak* *To whom correspondence should be addressed. Email: szostak@molbio.mgh.harvard.edu This
More informationPaper 4. Biomolecules and their interactions Module 22: Aggregates of lipids: micelles, liposomes and their applications OBJECTIVE
Paper 4. Biomolecules and their interactions Module 22: Aggregates of lipids: micelles, liposomes and their applications OBJECTIVE The main aim of this module is to introduce the students to the types
More informationTHE POLYMORPHIC PHASE BEHAVIOUR OF PHOSPHATIDYLETHANOLAMINES OF NATURAL AND SYNTHETIC ORIGIN
31 Biochimica et Biophysica Acta, 513 (1978) 31--42 Elsevier/North-Holland Biomedical Press BBA 78161 THE POLYMORPHIC PHASE BEHAVIOUR OF PHOSPHATIDYLETHANOLAMINES OF NATURAL AND SYNTHETIC ORIGIN A 31p
More informationSeries of Concentration-Induced Phase Transitions in Cholesterol/ Phosphatidylcholine Mixtures
2448 Biophysical Journal Volume 104 June 2013 2448 2455 Series of Concentration-Induced Phase Transitions in Cholesterol/ Phosphatidylcholine Mixtures István P. Sugár, * István Simon, and Parkson L.-G.
More informationLIPID POLYMORPHISM AND THE OCCURRENCE OF NON-BILAYER PHASES IN MODEL AND BIOLOGICAL MEMBRANES*
SEMINAR LIPID POLYMORPHISM AND THE OCCURRENCE OF NON-BILAYER PHASES IN MODEL AND BIOLOGICAL MEMBRANES* B de KRUIJFF, A J VERKLEIJ, J LEUNISSEN-BBJVELT, C J A van ECHTELD, W J GERRITSEN, C MOMBERS, P C
More informationA Microscopic Interaction Model of Maximum Solubility of Cholesterol in Lipid Bilayers
2142 Biophysical Journal Volume 76 April 1999 2142 2157 A Microscopic Interaction Model of Maximum Solubility of Cholesterol in Lipid Bilayers Juyang Huang and Gerald W. Feigenson Section of Biochemistry,
More informationPHOSPHOLIPID SURFACE BILAYERS AT THE AIR-WATER INTERFACE
PHOSPHOLIPID SURFACE BILAYERS AT THE AIR-WATER INTERFACE III. Relation Between Surface Bilayer Formation and Lipid Bilayer Assembly in Cell Membranes NORMAN L. GERSHFELD Laboratory ofbiochemical Pharmacology,
More informationModern Aspects of Colloid Science MICELLES
Modern Aspects of Colloid Science MICELLES critical micelle concentration (CMC) micellar shape determination of critical micelle concentration purity of surfactants Krafft temperature micellar equilibria
More informationFluid Mozaic Model of Membranes
Replacement for the 1935 Davson Danielli model Provided explanation for Gortner-Grendel lack of lipid and permitted the unit membrane model. Trans membrane protein by labelling Fry & Edidin showed that
More informationChemistry and Physics of Lipids
Chemistry and Physics of Lipids 164 (11) 177 183 Contents lists available at ScienceDirect Chemistry and Physics of Lipids journal homepage: www.elsevier.com/locate/chemphyslip Review Pivotal surfaces
More informationEffects of Cholesterol on Membranes: Physical Properties
Effects of Cholesterol on Membranes: Physical Properties Removes gel to liquid crystal phase transition New intermediate phase called liquid ordered - ordering of the membrane lipids due to condensation
More informationand controllable behavior - Supplementary Information
Metastability in lipid based particles exhibits temporally deterministic and controllable behavior - Supplementary Information Guy Jacoby, Keren Cohen, Kobi Barkan, Yeshayahu Talmon, Dan Peer, Roy Beck
More informationMethods and Materials
a division of Halcyonics GmbH Anna-Vandenhoeck-Ring 5 37081 Göttingen, Germany Application Note Micostructured lipid bilayers ANDREAS JANSHOFF 1), MAJA GEDIG, AND SIMON FAISS Fig.1: Thickness map of microstructured
More informationBIOPHYSICS II. By Prof. Xiang Yang Liu Department of Physics,
BIOPHYSICS II By Prof. Xiang Yang Liu Department of Physics, NUS 1 Hydrogen bond and the stability of macromolecular structure Membrane Model Amphiphilic molecule self-assembly at the surface and din the
More informationMovement of Cholesterol between Vesicles Prepared with Different Phospholipids or Sizes*
THE JOURNAL OF BIOLOGICAL CHEMISTRY 0 1985 by The American Society of Biological Chemists, Inc. Vol. 260, No. 7, Issue of April 10, pp. 4098-4102 1985 Printed in ~ s.a. Movement of Cholesterol between
More informationSurfactants. The Basic Theory. Surfactants (or surface active agents ): are organic compounds with at least one lyophilic. Paints and Adhesives
Surfactants Surfactants (or surface active agents ): are organic compounds with at least one lyophilic ( solvent-loving ) group and one lyophobic ( solvent-fearing ) group in the molecule. In the simplest
More informationWater adsorption isotherms and hydration forces for lysolipids and diacyl phospholipids
Water adsorption isotherms and hydration forces for lysolipids and diacyl phospholipids Derek Marsh Max-Planck-lnstitut, for biophysikalische Chemie, Abteilung Spektroskopie, D-3400 Gottingen, Federal
More informationTUTORIAL IN SMALL ANGLE X-RAY SCATTERING ANALYSIS
TUTORIAL IN SMALL ANGLE X-RAY SCATTERING ANALYSIS at the Abdus Salam International Center of Theoretical Physics (ICTP) Heinz Amenitsch Sigrid Bernstorff Michael Rappolt Trieste, 15. May 2006 (14:30-17:15)
More informationSelf-assembled nanostructures soft and hard matter
Hands-On Nano-Technology course Nano-Science Center University of Copenhagen Self-assembled nanostructures soft and hard matter One-day workshop, August 12, 2004 Division of Physical Chemistry 1, Center
More informationThe main biological functions of the many varied types of lipids include: energy storage protection insulation regulation of physiological processes
Big Idea In the biological sciences, a dehydration synthesis (condensation reaction) is typically defined as a chemical reaction that involves the loss of water from the reacting molecules. This reaction
More informationEffects of Anesthetics on Lipid Polymorphism
Effects of Anesthetics on Lipid Polymorphism P. R. Cullis, A. P. Hornby, and M. J. Hope Department 01 Biochemistry, University of British Columbia, Vancouver V6T I W5, British Columbia, Canada The molecular
More informationChanges in Dipalmitoyl Lecithin Multilayers (gel-liquid crystral transition/noncooperative/transition temperature)
Proc. Nat. Acad. Sci. USA Vol. 68, No. 7, pp. 1572-1576, July 1971 Laser Raman Investigation of the Effect of Cholesterol on Conformational Changes in Dipalmitoyl Lecithin Multilayers (gel-liquid crystral
More informationThermotropic and barotropic phase transitions on diacylphosphatidylethanolamine bilayer membranes
Thermotropic and barotropic phase transitions on diacylphosphatidylethanolamine bilayer membranes Hitoshi Matsuki 1, *, Shigeru Endo 2, Ryosuke Sueyoshi 2, Masaki Goto 1, Nobutake Tamai 1 and Shoji Kaneshina
More informationIon Diffusion Selectivity in Lecithin-Water Lamellar Phases
Ion Diffusion Selectivity in Lecithin-Water Lamellar Phases Y. LANGE and C. M. GARY BOBO From the Laboratoire de Physiologie Cellulaire, College de France, Paris, France. Dr. Lange's present address is
More informationbelieved to have an effect upon the distribution of chain ends in the membrane as well as the order parameter
BRIEF COMMUNICATION PHOSPHOLIPID PACKING AND CONFORMATION IN SMALL VESICLES REVEALED BY TWO-DIMENSIONAL 'H NUCLEAR MAGNETIC RESONANCE CROSS-RELAXATION SPECTROSCOPY ZHEN-CHEN XU AND DAVID S. CAFISO Department
More informationDepartment of Chemistry, University of Arizona, Tucson, Arizona 85721
December 31, 1990 Pages 1231-1238 INFLUENCES OF MEMBRANE CURVATURE IN LIPID HEXAGONAL PHASES STUDIED BY DEUTERIUM NMR SPECTROSCOPY Ig Robin L. Thurmond, G6ran Llndblom, and Michael F. Brown Department
More informationCorrelation Between Lipid Plane Curvature and Lipid Chain Order
Biophysical Journal Volume 70 June 1996 2747-2757 2747 Correlation Between Lipid Plane Curvature and Lipid Chain Order Michel Lafleur,* Myer Bloom,$ Eric F *D6partement de chimie, Universit6 de Montreal,
More informationPhase behavior of charged lipid bilayer membranes with added electrolyte
JOURNAL OF CHEMICAL PHYSICS VOLUME 119, NUMBER 2 8 JULY 2003 Phase behavior of charged lipid bilayer membranes with added electrolyte Shigeyuki Komura, a) Hisashi Shirotori, and Tadashi Kato Department
More informationStructure and Phase Behaviour of Binary Mixtures of Cholesterol with DPPC and DMPC
Chapter 3 Structure and Phase Behaviour of Binary Mixtures of Cholesterol with DPPC and DMPC 3.1 Introduction As discussed in chapter 1, phospholipids and cholesterol are important constituents of plasma
More informationN-Succinyldioleoylphosphatidylethanolamine: structural preferences in pure and mixed model membranes
Biochimica et Biophysica Acta 937 (1988) 31-41 Elsevier 31 BBA 73814 N-Succinyldioleoylphosphatidylethanolamine: structural preferences in pure and mixed model membranes Rajiv Nayar a7 *, Colin P.S. Tilcock
More informationWhat is the intermolecular force present in these molecules? A) London B) dipole-dipole C) hydrogen bonding D) ion-dipole E) None. D.
REVIEW SHEET CHP 7, FRST AND DEAL 1. (7.1) Types of Attractive Forces (Intermolecular forces (IMF)). IMF s are attractive forces between molecules due to electrostatic attraction. Therefore a molecule
More informationWhy cholesterol should be found predominantly in the cytoplasmic leaf of the plasma membrane
Why cholesterol should be found predominantly in the cytoplasmic leaf of the plasma membrane H. Giang and M. Schick Department of Physics, University of Washington,Seattle, WA 98195 July 21, 2014 Abstract
More informationNeutron reflectivity in biology and medicine. Jayne Lawrence
Neutron reflectivity in biology and medicine Jayne Lawrence Why neutron reflectivity studies? build up a detailed picture of the structure of a surface in the z direction n e u tro n s in n e u tro n s
More informationMolecular Packing Parameter and Surfactant Self-Assembly: The Neglected Role of the Surfactant Tail
Langmuir 2002, 18, 31-38 31 Molecular Packing Parameter and Surfactant Self-Assembly: The Neglected Role of the Surfactant Tail R. Nagarajan Department of Chemical Engineering, The Pennsylvania State University,
More informationPhospholipid Component Volumes: Determination and Application to Bilayer Structure Calculations
734 Biophysical Journal Volume 75 August 1998 734 744 Phospholipid Component Volumes: Determination and Application to Bilayer Structure Calculations Roger S. Armen, Olivia D. Uitto, and Scott E. Feller
More informationThe Interaction between Lipid Bilayers and Biological Membranes. Chapter 18
The Interaction between Lipid Bilayers and Biological Membranes Chapter 18 Introduction Membrane & Phospholipid Bilayer Structure Membrane Lipid bilayer 2 Introduction Forces Acting between Surfaces in
More informationChapter 7: Membranes
Chapter 7: Membranes Roles of Biological Membranes The Lipid Bilayer and the Fluid Mosaic Model Transport and Transfer Across Cell Membranes Specialized contacts (junctions) between cells What are the
More informationMOLECULAR DYNAMICS SIMULATION OF MIXED LIPID BILAYER WITH DPPC AND MPPC: EFFECT OF CONFIGURATIONS IN GEL-PHASE
MOLECULAR DYNAMICS SIMULATION OF MIXED LIPID BILAYER WITH DPPC AND MPPC: EFFECT OF CONFIGURATIONS IN GEL-PHASE A Thesis Presented to The Academic Faculty by Young Kyoung Kim In Partial Fulfillment of the
More informationLecture 15 The Lipid Bilayer: A Dynamic Self- Assembled Structure of Multiple Lipid Classes
Lecture 15 The Lipid Bilayer: A Dynamic Self- Assembled Structure of Multiple Lipid Classes LIPIDS-Biological molecules with low solubility in water and high solubility in non-polar solvents -Lipids form
More informationMaterial Property Characteristics for Lipid Bilayers Containing Lysolipid
Biophysical Journal Volume 75 July 1998 321 330 321 Material Property Characteristics for Lipid Bilayers Containing Lysolipid Doncho V. Zhelev Department of Mechanical Engineering and Materials Science,
More informationCell Membrane Structure (1.3) IB Diploma Biology
Cell Membrane Structure (1.3) IB Diploma Biology Essential idea: The structure of biological membranes makes them fluid and dynamic http://www.flickr.com/photos/edsweeney/6346198056/ 1.3.1 Phospholipids
More informationL ysophospholipids, while quantitatively minority components
816 Biochemistry 1986, 25, 8 16-822 Polymorphic Phase Behavior of Unsaturated Lysophosphatidylethanolamines: A 31P NMR and X-ray Diffraction Study? C. P. S. Tilcock,* P. R. Cullis, and M. J. Hope Department
More informationThe effect of hydrostatic pressure on membrane-bound proteins
Brazilian Journal of Medical and Biological Research (2005) 38: 1203-1208 High pressure studies on membrane-associated proteins ISSN 0100-879X Review 1203 The effect of hydrostatic pressure on membrane-bound
More informationChain Length Dependence
Biophysical Journal Volume 71 August 1996 885-891 885 Structure of Gel Phase Saturated Lecithin Bilayers:. Temperature and Chain Length Dependence W.-J. Sun,* S. Tristram-Nagle,# R. M. Suter,* and J. F.
More informationModel for measurement of water layer thickness under lipid bilayers by surface plasmon resonance
Model for measurement of water layer thickness under lipid bilayers by surface plasmon resonance Koyo Watanabe Unit of Measurement Technology, CEMIS-OULU, University of Oulu, PO Box 51, 87101 Kajaani,
More informationInorganic compounds: Usually do not contain carbon H 2 O Ca 3 (PO 4 ) 2 NaCl Carbon containing molecules not considered organic: CO 2
Organic Chemistry The study of carbon-containing compounds and their properties. Biochemistry: Made by living things All contain the elements carbon and hydrogen Inorganic: Inorganic compounds: All other
More informationP NMR in lipid membranes. CSA recoupling.
31 P NMR in lipid membranes. CSA recoupling. Ludovic BERTHELT, Dror E. WARSCHAWSKI & Philippe F. DEVAUX 1 1 Laboratoire de physico-chimie moléculaire des membranes biologiques UPR 9052 Alpine conference
More informationChemistry and Physics of Lipids 127 (2004)
Chemistry and Physics of Lipids 127 (2004) 153 159 The kinetics and mechanism of the formation of crystalline phase of dipalmitoylphosphatidylethanolamine dispersed in aqueous dimethyl sulfoxide solutions
More informationCoarse grained simulations of Lipid Bilayer Membranes
Coarse grained simulations of Lipid Bilayer Membranes P. B. Sunil Kumar Department of Physics IIT Madras, Chennai 600036 sunil@iitm.ac.in Atomistic MD: time scales ~ 10 ns length scales ~100 nm 2 To study
More informationGen. Physiol. Biophys. (1988), 7,
Gen. Physiol. Biophys. (1988), 7, 633-642 633 The Lateral Order of Dipalmitoylphosphatidylcholine Model Membranes in the Presence of N-alkyl-N,N,N-trimethylammonium Ions as Studied by Raman Spectroscopy*
More informationBiological Membranes. Lipid Membranes. Bilayer Permeability. Common Features of Biological Membranes. A highly selective permeability barrier
Biological Membranes Structure Function Composition Physicochemical properties Self-assembly Molecular models Lipid Membranes Receptors, detecting the signals from outside: Light Odorant Taste Chemicals
More informationRole of ceramide 1 in the molecular organization of the stratum corneum lipids
Role of ceramide 1 in the molecular organization of the stratum corneum lipids J. A. Bouwstra, 1, * G. S. Gooris,* F. E. R. Dubbelaar,* A. M. Weerheim, A. P. IJzerman* and M. Ponec Leiden/Amsterdam Center
More informationQuiz 8 Introduction to Polymers (Chemistry)
051117 Quiz 8 Introduction to Polymers (Chemistry) (Figures from Heimenz Colloid Sci.) 1) Surfactants are amphiphilic molecules (molecules having one end hydrophobic and the other hydrophilic) and are
More informationSupplementary Information: Liquid-liquid phase coexistence in lipid membranes observed by natural abundance 1 H 13 C solid-state NMR
Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is the wner Societies 28 Supplementary Information: Liquid-liquid phase coexistence in lipid membranes observed
More informationA Conductometric Study of Interaction between Sodium Dodecyl Sulfate and 1-Propanol, 1-Butanol, 1-Pentanol and 1-Hexanol at Different Temperatures
1 J. Surface Sci. Technol., Vol 24, No. 3-4, pp. 139-148, 2008 2008 Indian Society for Surface Science and Technology, India. A Conductometric Study of Interaction between Sodium Dodecyl Sulfate and 1-Propanol,
More informationSupplementary information. Membrane curvature enables N-Ras lipid anchor sorting to. liquid-ordered membrane phases
Supplementary information Membrane curvature enables N-Ras lipid anchor sorting to liquid-ordered membrane phases Jannik Bruun Larsen 1,2,3, Martin Borch Jensen 1,2,3,6, Vikram K. Bhatia 1,2,3,7, Søren
More informationSmall angle neutron scattering study of mixed micelles of oppositely charged surfactants
PRAMANA c Indian Academy of Sciences Vol. 71, No. 5 journal of November 2008 physics pp. 1039 1043 Small angle neutron scattering study of mixed micelles of oppositely charged surfactants J V JOSHI 1,,
More informationRole of Ethanol in the Modulation of Miscibility Transition in Model Lipid Bilayers
Role of Ethanol in the Modulation of Miscibility Transition in Model Lipid Bilayers Jialing Li 1 Advisor: Dr. Sarah L. Keller 2 Department of Chemistry, University of Washington, Seattle, WA 1,2 Department
More informationPROPERTIES OF BILAYER MEMBRANES IN THE PHASE TRANSITION OR PHASE SEPARATION REGION
24 Biochimica et Biophysica Acta, 557 (1979) 24--31 ElsevierNorth-Holland Biomedical Press BBA 78523 PROPERTIES OF BILAYER MEMBRANES IN THE PHASE TRANSITION OR PHASE SEPARATION REGION S. MARCELJA and J.
More informationTHE INS AND OUTS OF YOUR SKIN. Emma Sparr Physical Chemistry Lund University
THE INS AND OUTS OF YOUR SKIN Emma Sparr Physical Chemistry Lund University The skin - A Responding Barrier Membrane stratum corneum (10 20 µm) Water CO 2 Temperature ph 5.5 O 2 Moisturizers, Drugs etc
More informationPhysicochemical Properties of PEG-Grafted Liposomes
1238 Chem. Pharm. Bull. 50(9) 1238 1244 (2002) Vol. 50, No. 9 Physicochemical Properties of PEG-Grafted Liposomes Supaporn SRIWONGSITANONT and Masaharu UENO* Faculty of Pharmaceutical Sciences, Toyama
More information8 Influence of permeation modulators on the behaviour of a SC lipid model mixture
8 Influence of permeation modulators on the behaviour of a SC lipid model mixture 8.1 Introduction In the foregoing parts of this thesis, a model membrane system of SC lipids has been developed and characterized.
More informationChem 431A-L25-F 07 admin: Last time: : soaps, DG s and phospholipids, sphingolipids and cholesterol.
Chem 431A-L25-F'07 page 1 of 5 Chem 431A-L25-F 07 admin: Last time: : soaps, DG s and phospholipids, sphingolipids and cholesterol. Today: distinguish between various lipids specific lipids and their structures.
More informationThe effect of cholesterol on the solubilization of phosphatidylcholine bilayers by the non-ionic surfactant Triton X-100
Chemistry and Physics of Lipids 135 (2005) 69 82 The effect of cholesterol on the solubilization of phosphatidylcholine bilayers by the non-ionic surfactant Triton X-100 E. Schnitzer, M.M. Kozlov, D. Lichtenberg
More informationISM08. Surfactants II Chapters 3 and 4
ISM08 Surfactants II Chapters 3 and 4 1 Topics Emulsions Foam Curvature Laplace pressure Packing factor Lyotropic phases Membranes and vesicles 2 Emulsions Emulsions are dispersions of immiscible or partially
More informationSimulationen von Lipidmembranen
Simulationen von Lipidmembranen Thomas Stockner thomas.stockner@meduniwien.ac.at Molecular biology Molecular modelling Membranes environment Many cellular functions occur in or around membranes: energy
More informationTest Bank for Lehninger Principles of Biochemistry 5th Edition by Nelson
Test Bank for Lehninger Principles of Biochemistry 5th Edition by Nelson Link download full: http://testbankair.com/download/test-bank-forlehninger-principles-of-biochemistry-5th-edition-by-nelson/ Chapter
More informationPhase Transition Behaviours of the Supported DPPC Bilayer. Investigated by Sum Frequency Generation (SFG) and Atomic Force
Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics. This journal is the Owner Societies 2015 Supporting Information for Phase Transition Behaviours of the Supported DPPC Bilayer
More informationA Cloud Point Study on the Micellar Growth of an Amphiphilic Drug in the Presence of Alcohol and Ionic Surfactant
J. Phys. Chem. B 2003, 107, 8689-8693 8689 A Cloud Point Study on the Micellar Growth of an Amphiphilic Drug in the Presence of Alcohol and Ionic Surfactant Eui Jung Kim and Dinesh O. Shah*, Department
More informationColloid Chemistry. Lecture #2 Association colloid
Colloid Chemistry Lecture #2 Association colloid 1 https://ilustracionmedica.wordpress.com/2014/08/27/fisicos-haciendo-medicina-john-tyndall/ Solution Classical vs. Colloid solution Tyndall effect Increased
More informationStructure of DNA-CTAB-hexanol complexes
Structure of DNA-CTAB-hexanol complexes Rema Krishnaswamy, 1 Georg Pabst, 2 Michael Rappolt, 2 V. A. Raghunathan, 1 and A. K. Sood 3 1 Raman Research Institute, Bangalore 560 080, India 2 Institute of
More information1.4 Page 1 Cell Membranes S. Preston 1
AS Unit 1: Basic Biochemistry and Cell Organisation Name: Date: Topic 1.3 Cell Membranes and Transport Page 1 1.3 Cell Membranes and Transport from your syllabus l. Cell Membrane Structure 1. Read and
More informationTHE ROLE OF NONBILAYER LIPID STRUCTURES IN THE FUSION OF HUMAN ERYTHROCYTES INDUCED BY LIPID FUSOGENS
82 Biochimica et Biophysica Acta, 640 (1981) 82--90 Elsevier/North-Holland Biomedical Press BBA 79044 THE ROLE OF NONBILAYER LIPID STRUCTURES IN THE FUSION OF HUMAN ERYTHROCYTES INDUCED BY LIPID FUSOGENS
More informationPak K. Yuet M.Sc., Chemical Engineering (1990) Queen's University B.Eng., Chemical Engineering (1988) Technical University of Nova Scotia
61/ Theoretical and Experimental Studies of Vesicle Formation in Surfactant Mixtures by Pak K. Yuet M.Sc., Chemical Engineering (1990) Queen's University B.Eng., Chemical Engineering (1988) Technical University
More informationAFM In Liquid: A High Sensitivity Study On Biological Membranes
University of Wollongong Research Online Faculty of Science - Papers (Archive) Faculty of Science, Medicine and Health 2006 AFM In Liquid: A High Sensitivity Study On Biological Membranes Michael J. Higgins
More informationLysophospholipids and fat digestibility
1 Lysophospholipids and fat digestibility Fig.1 Micelle Fat is composed mainly of triglycerides. The problem with fat digestion is that it takes place in an aqueous environment, when fat is not water soluble.
More informationSupplementary Information: Supplementary Note 1: Confirmation of Complex 3D Self-Assembly and Assignment of Lyotropic Phases
Supplementary Information: Supplementary Note 1: Confirmation of Complex 3D Self-Assembly and Assignment of Lyotropic Phases This section shows SAXS patterns from different lyotropic phases we observed
More informationHow to maximize fat energy? Swine. Poultry. Shrimp. Technical brochure about the molecular structure and mode of action of lysolecithins
Introduction «Lecithin and lysolecithin «Normal fat digestion «Mode of action lysolecithins «Conclusions «Swine Poultry Fish How to maximize fat energy? Shrimp Technical brochure about the molecular structure
More informationLIPID POLYMORPHISM AND THE FUNCTIONAL ROLES OF LIPIDS IN BIOLOGICAL MEMBRANES
399 Biochimica et Biophysica Acta, 559 (1979) 399 420 Elsevier/North-Holland Biomedical Press BBA 85201 LIPID POLYMORPHISM AND THE FUNCTIONAL ROLES OF LIPIDS IN BIOLOGICAL MEMBRANES P.R. CULLIS a and B.
More information