Bio-Organic Game 1. A unique two carbon aldose carbohydrate is possible, but not technically considered a carbohydrate, 2- hydroxyethanal

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1 io-rganic Game 1 arbohydrates The following carbohydrates show a small sampling of ature s choices for energy use, structural support and also serve as recognition targets in cells. ature almost exclusively picks one enantiomer of a pair, though apparently some bacteria can both enantiomers. When drawn as a Fischer projection the common stereoisomer has the second to the last on the right side. In iochemistry, this is referred to as the D isomer. If the second to last were on the left side in a Fischer projection it would be referred to as the L isomer. There is no logical reason for these designations. They must be memorized, as do the positions of all of the other groups up the chain. educing carbohydrates have an aldehyde carbon at 1 and can be 2s, s, 4s, 5s, 6s or more in length. Glucose is probably the most famous of the carbohydrates. ome of these are shown below. ow many chiral centers does each example have? Through tautomeric changes an aldehyde carbohydrate (glucose) can be converted into a keto carbohydrate (fructose). ow many stereoisomers are possible for each length of carbon? What are the absolute configurations of any chiral centers? What stereochemical relationship does the first stereoisomer as A (then,, etc.) have to the others? Are there any meso structures. (ee problem below.) A unique two carbon aldose carbohydrate is possible, but not technically considered a carbohydrate, 2- hydroxyethanal achiral glycoaldehyde Three carbon aldose carbohydrates two possible (enantiomers), both are 2,-dihydroxypropanal 2 D-glyceraldehyde 2 L-glyceraldehyde top D 2 generic carbohydrate When the second to the last "" is on the right side, biochemists refer to it as a "D" carbohydrate. Most carbohydrates in nature are "D". Most amino acids, on the other hand are "L" with a " 2 " on the left side. 2 2 L generic amino acid Four carbon aldose carbohydrates four possible, all are 2,,4-trihydroxybutanal (enantiomers and diastereomers) 2 D-erythrose 2 L-erythrose 2 D-threose 2 L-threose iochem names are all different. rganic names are easier. All of these are 2,,4-trihydroxybutanal. 1 = (2,),,4-trihydroxybutanal 2 = (2,),,4-trihydroxybutanal = (2,),,4-trihydroxybutanal 4 = (2,),,4-trihydroxybutanal Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

2 io-rganic Game 2 Five carbon aldose carbohydrates eight possible, all are 2,,4,5-tetrahydroxypentanal (enantiomers and diastereomers) 2 D-ribose L-ribose D-arabinose L-arabinose D-xylose L-xylose D-lyxose 2 L-lyxose ix carbon aldose carbohydrates 16 possible, all are 2,,4,5,6-pentahydroxyhexanal (enantiomers and diastereomers) 2 D-allose L-allose D-altrose L-altrose D-glucose L-glucose D-gluose 2 L-gluose 2 D-mannose L-mannose D-galactose L-galactose D-idose L-idose D-talose 2 L-talose 2 D-allose = D-allose Without the dashes and wedges, these two carbohydrates look the same 2 D-glucose = D-glucose Without the dashes and wedges, these two carbohydrates look the same Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

3 io-rganic Game roblem What would happen to the number of stereoisomers in each case above if the top aldehyde functionality were reduced to an alcohol functionality (a whole other set of carbohydrates!)? A generic structure is provided below to show the transformation. ature s some of these too. ow many chiral centers does each example have? ow many stereoisomers are possible for each length of carbon? What are the absolute configurations of any chiral centers? pecify the first stereoisomer as A (then,, etc.) and state what each relationship is to the others. Are there any meso structures. 2 educe aldehyde to alcohol 2 2 Three carbon tri-ol carbohydrate = becomes only one structure (glycerol), which is achiral Four carbon tetra-ol carbohydrates = becomes three stereoisomers (one meso pattern) Five carbon penta-ol carbohydrates = becomes four stereoisomers (two meso patterns, one duplication) ix carbon hexa-ol carbohydrates = becomes ten stereoisomers (two meso patterns, two duplications) D-glucose is the most common choice of the 6 carbon examples above (can you think of a possible reason?). Even though it is a single sugar, ature can arrange glucose in many possible ways. nly a few are shown below. open chain D-glucose (< 1% in body) 2 rotation around the 1-2 bond 2 and D-glucose (furanose) (< 1% in body) pyranose ring of glucose (6 atoms), the aldehyde oxygen can be on the top = equatorial (called ) or on the bottom = axial (called ), both are observed in the body cyclization controlled by enzymes cyclization controlled by enzymes otice a similarity to Vit.? 4 enzyme controlled reactions, we are missing one of them 2 bottom -D-glucose (pyranose) ( % in body) 2 top -D-glucose (pyranose) ( 66% in body) Vit. 2 open chain D-glucose pyranoses (6 atom ring) furanoses (5 atom ring) Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

4 io-rganic Game 4 etc. etc etc. 2 etc. ellulose consists of long flat chains of glucose molecules (about 15,000) connected with the linkage, about 40 chains per fiber. It is said that cellulose accounts for about 1/2 of all the carbon in the biosphere and about kg of cellulose are synthesized and degraded every year. About 90% of cotton is cellulose. In our plant food it is referred to as dietary fiber or roughage. uminants and termites can break down cellulose with the help of microorganisms. Glycogen (our glucose storage system) consists of helicies of glucose molecules connected with the linkage. We have about 2000 Kcals of energy stored in this way in our liver. When blood levels of glucose get low, our liver starts to release glucose from our glycogen stores. When you start to run out of glycogen your body switches over to fat metabolism to glucose (gluconeogenisis). (1,4) linkages are shown but there are also some (1,6) linkages in glycogen. Disaccharides are two sugars linked together ( or ). ommon carbohydrate possibilities have, 4, 5 and 6 structures and the carbonyl group can be an aldehyde or a ketone. As mentioned above, the 6 sugars can be six atom heterocycles (pyranoses such as glucose) or five atom heterocycles (furanoses such as fructose). ucrose and lactose are two of the more famous disaccarides. "Glucose" in the general class of pyranoses. "Fructose" in the general class of furanoses. sucrose - found in beets and sugar cane acetal linkage ketal linkage -D-glucopyranosyl-(1 2)- -D-fructofuranoside lactose - found in mother's milk acetal linkage hemi-acetal linkage "galactose" "glucose" -D-galactopyranosyl-(1 4)- -D-glucopyranose The nomenclature of biochemistry often appears more complicated than the nomenclature of organic chemistry. Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

5 io-rganic Game 5 There are approximately 60 amino sugars known, having many important functions. - acetylglucosamine is part of a biopolymer in bacterial cell walls and a major component of the cell walls of most fungi. It is also the monomeric unit of the polymer chitin, which forms the outer coverings of insects and crustaceans. When polymerized with glucoronic acid, it forms hyaluronic acid, which is a polymer with a molecular weight in the millions. A 150 pound body has about 15 grams of hyaluronic acid in it. glucoronic acid n hyluronan -acetyl-d-glucosamine -acetyl-d-glucosamine Glycolipids can serve as markers for cellular recognition and are found on the outer surface of all eukaryotic cell membranes. They extend from the phospholipid bilayer into the aqueous environment outside the cell where it acts as a recognition site for specific chemicals as well as helping to maintain the stability of the membrane and attaching cells to one another to form tissues. glycolipids = fatty acid chain glycero glyco lipids lood types are based, in part, on carbohydrate coatings linked to lipid molecules on the outer cell membranes. There is also a soluble form linked to proteins in the blood. About 75% of type A individuals have a repeat of the terminal sugars. Type A (4% in the U) have both A and patterns on their cell surfaces and are universal acceptors. There is some variation in the position number of the connections and the / linkage is not indicated. cience ews (vol 151, p 24, ) discusses enzymes from chicken livers (type A) and coffee beans (type ) that can cleave the single sugar at the end of the cell coatings. This would convert type A and type to type, which would allow for universal donation. The article discusses the possible commercial production for blood donations. There are over 7,000,000,000 (billion) people on the earth. Every one of us has a unique biochemical profile that is uniquely recognized by our immune system. The blood types give you a hint at how this is possible. Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

6 io-rganic Game 6 type (45% in U) universal donor cell membrane gluc galac -acet galac This sequence is the same in all blood types (type ) fucose The linkages are unspecified here. fucose gluc galac -acet galac galac type A (40% in U) galactose cell membrane The extra galactose s this type A. fucose glucose type (11% in U) cell membrane gluc galac -acet galac The extra -acetylgalactosamine s this type. fucose -acet -acetylgalactosamine Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

7 io-rganic Game 7 ycles 1. Glycolysis simple version (not all steps are shown in the usual cycyle) glucose 2 (glycolysis) glucose AT glucokinase glucose-6-phosphate phosphoglucose isomerase 2 2 fructose-6-phosphate phosphofructokinase fructose-1,6-bisphosphate aldolase triose 2 2 phosphate 2 isomerase dihydroxyacetone phosphate glyceraldehyde--phosphate (x2) (made into glyceraldehyde--phosphate) 2 AD + + glyceraldehyde--phosphate dehydrogenase 1,-bisphosphoglycerate alanine cysteine glycine serine threonine tryptophan 2 AD AT 2 lactate AT phosphoglycerate mutase glyceraldehyde--phosphate dehydrogenase phosphoglycerate kinase pyrovate kinase enolase 1,-bisphosphoglycerate 2-phosphoglycerate phosphoenol pyruvate (E) pyruvate (x2) -phosphoglycerate -oa acetyl o-a...or transported in blood to liver and oxidized back to pyruvate and made back into glucose via gluconeogenosis Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

8 io-rganic Game 8 Glycolysis long version Glycolysis glycogen glycogen - glucose polymer 1a 1b cleave glucose open acetal open chain glucose hemi-acetal 2 cyclic glucose AT ene-diol open chain fructose-6-phosphate 12 6 AD+ lactate ethanol 11 tautomerization hemithioacetal mixed anhydride 7 open chain glucose-6-phosphate cyclic fructose-6-phosphate glyceraldehyde--phosphate dihydroxyacetone phosphate 19 AD AD 21 tautomerization ethanal 5 hemi-ketal pyruvate via ene-diol 18 open acetal 8 4 AT cyclic glucose-6-phosphate cyclic fructose-1,6-bisphosphate reverse hemi-ketal 9 reverse aldol 10 open chain fructose-1,6-bisphosphate AT ,-bisphosphoglycerate -phosphoglycerate AD 10b AT oa acetyl o-a imidazole, phosphate on phosphoenol pyruvate (E) 17 imidazole, phosphate off elimination of water (Mg +2 helps) 2,-bisphosphoglycerate 16 2-phosphoglycerate Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

9 io-rganic Game 9 Glycolysis step by step Mechanism steps without arrows. : = base and +- = acid. Add in necessary arrows to show electron movement. tereochemistry is omitted. Each step is under enzyme control. ossible answers are shown below. 1 glycogen 1b glycogen cyclic glucose open chain glucose glycogen 1a cleave glucose 1b open acetal 2 AT cyclic glucose inorganic ester glycogen hemi-acetal AD 5 4 cyclic glucose 2 open chain glucose cyclic glucose cyclic glucose-6-phosphate open acetal cyclic glucose-6-phosphate open chain glucose-6-phosphate Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

10 io-rganic Game 10 5 open chain glucose-6-phosphate tautomerization ene-diol 6 ene-diol tautomerization open chain fructose-6-phosphate 7 hemi-ketal open chain fructose-6-phosphate cyclic fructose-6-phosphate 8 AD cyclic fructose-6-phosphate AT AT cyclic fructose-1,6-bisphosphate 9 reverse hemi-ketal cyclic fructose-1,6-bisphosphate open chain fructose-1,6-bisphosphate Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

11 io-rganic Game b open chain fructose-1,6-bisphosphate dihydroxyacetone phosphate reverse aldol via ene-diol 10b glyceraldehyde--phosphate dihydroxyacetone phosphate tautomerization ene-diol 10 imine alternative to keto retroaldol (actually protonated iminium ion) tautomerization glyceraldehyde--phosphate via ene-diol hydrolyze imine Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

12 io-rganic Game hemithioacetal glyceraldehyde--phosphate hemi-thioacetal 12 AD+ oxidation AD 1 mixed anhydride thioester 1,-bisphosphoglycerate 14 AD 1,-bisphosphoglycerate AT AT -phosphoglycerate 15 -phosphoglycerate imidazole phosphate 2,-bisphosphoglycerate Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

13 io-rganic Game ,-bisphosphoglycerate imidazole 2-phosphoglycerate 17 2-phosphoglycerate elimination of water (Mg +2 helps) phosphoenol pyruvate (E) 18 phosphoenol pyruvate (E) AD AT pyruvate AT 19 a reaction goes in both directions reduction pyruvate AD lactate AD+ 19 b lactate AD+ oxidation pyruvate AD Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc

14 io-rganic Game 14 Y:\files\classes\io-organic Game\499 carbohydrate and glycolysis cycle.doc pyruvate T ylid 20-2 elimination ethanal addition T ylid ethanal ethanol AD 21 AD AD+ 22 elimination ethanal T ylid from step 20