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Carbs

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Carbs

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  1. Carbs

  2. Greatest biomass of biopolymers Polyhydroxy aldehydes and ketones Many functions Structure Fuel Energy storage Adhesion Lubrication signalling tagging for siting, function Carbohydrates

  3. Degree of polymerization • Monosaccharides • Storage, energy modules, metabolic intermediates • Disaccharides, trisaccharides • Storage • Oligosaccharides • Molecular Recognition • Polysaccharides • Structure, storage

  4. Fisher Projectionsof chiral monosaccharides • Next-to-bottom carbon hydroxyl extends to the right --- a D sugar; cf. with L amino acid

  5. fig 9-3a

  6. fig 9-3b

  7. Hemiacetal/-ketal structures of monosaccharides • Reaction of an aldehyde or ketone with an alcohol • favorable intramolecular reaction

  8. fig 9-5

  9. Intramolecular hemiacetals/ketals of monosaccharides are RINGS stereo chair open chain Haworth

  10. Anomers • Sugars that vary in configuration about the anomeric (aldehydic or ketonic) carbon • Convention:  = hydroxyl down,  = hydroxyl up

  11. fig 9-6

  12. Fig 9-7

  13. Hexose derivatives • Amino sugars • Acetamido sugars • Deoxy sugars • Fucose, rhamnose, abequose • Other glycosidic additives • Lactic acid • Oxidized sugars • Sugar phosphates

  14. Fig 9-9

  15. Reducing sugars • Aldehydes are oxidized by mild agents • Cu2+ + aldehyde (or -hydroxyketone)  Cu+ + acid • Disaccharides react more slowly

  16. Fig 9-10

  17. Disaccharides • Glycosidic linkage • Acetal (or ketal) formed. 2nd monosaccharide acts as an alcohol

  18. Fig 9-5 (repeat)

  19. Disaccharide, cont • Reducing • one anomeric C not glycosidically linked • Nonreducing • Both anomeric C’s linked (fructose, trehalose)

  20. Disaccharide nomenclature • Nonreducing end on left • Linkage –(nm)- • Reducing end Note that nonreducing end configuration is fixed Reducing end can mutarotate, thus 1st component given as - or -, 2nd ambiguous (next slide)

  21. Fig 9-11

  22. Table 9-1

  23. Important disaccharides • Maltose • Lactose • Sucrose • Trehalose

  24. Fig 9-12

  25. Table 9-2

  26. Storage polysaccharides • Plants • Starch • Amylose – llinear polyglucose, -1,4 linked (-D-glucopyranosyl-(14)-…), M ~ 106 • Amylopectin –polyglucose, -1,4 linked, -1,6 branched 1 per 24-30, M ~ 108 • Animals • Glycogen • polyglucose, -1,4 linked, -1,6 branched 1 per 24-30, M ~ 106

  27. Fig 9-15 b

  28. Fig 9-14 0.10 m 1.0 m

  29. fig 9-15

  30. Structural Polysaccharides • Plants • Cellulose – linear polyglucose •  1,4 linked • M ~ 106 • Certain exoskeletons • Chitin – linear poly(N-acetyl-D-glucosamine) •  1,4 linked

  31. Fig 9-17a and 9-18 Cellulose Chitin

  32. Structural polysaccharides, cont • Bacterial cell walls – peptidoglycans • Extracellular matrix of multicellular animals - glycosaminoglycans

  33. Fig 9-19

  34. Fig 9-20

  35. Sugar-protein and sugar-lipid conjugates • Glycoconjugates • Proteoglycans • Glycosaminoglycans bound to proteins • Glycoproteins • Oligosaccharides bound to proteins • Glycolipids • Oligosaccharides bound to lipids (heads of membrane lipids)

  36. Fig 9-29

  37. Fig 9-27