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Carbs. Greatest biomass of biopolymers Polyhydroxy aldehydes and ketones Many functions Structure. Fuel Energy storage Adhesion Lubrication signalling tagging for siting, function. Carbohydrates. Degree of polymerization. Monosaccharides
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Greatest biomass of biopolymers Polyhydroxy aldehydes and ketones Many functions Structure Fuel Energy storage Adhesion Lubrication signalling tagging for siting, function Carbohydrates
Degree of polymerization • Monosaccharides • Storage, energy modules, metabolic intermediates • Disaccharides, trisaccharides • Storage • Oligosaccharides • Molecular Recognition • Polysaccharides • Structure, storage
Fisher Projectionsof chiral monosaccharides • Next-to-bottom carbon hydroxyl extends to the right --- a D sugar; cf. with L amino acid
Hemiacetal/-ketal structures of monosaccharides • Reaction of an aldehyde or ketone with an alcohol • favorable intramolecular reaction
Intramolecular hemiacetals/ketals of monosaccharides are RINGS stereo chair open chain Haworth
Anomers • Sugars that vary in configuration about the anomeric (aldehydic or ketonic) carbon • Convention: = hydroxyl down, = hydroxyl up
Hexose derivatives • Amino sugars • Acetamido sugars • Deoxy sugars • Fucose, rhamnose, abequose • Other glycosidic additives • Lactic acid • Oxidized sugars • Sugar phosphates
Reducing sugars • Aldehydes are oxidized by mild agents • Cu2+ + aldehyde (or -hydroxyketone) Cu+ + acid • Disaccharides react more slowly
Disaccharides • Glycosidic linkage • Acetal (or ketal) formed. 2nd monosaccharide acts as an alcohol
Disaccharide, cont • Reducing • one anomeric C not glycosidically linked • Nonreducing • Both anomeric C’s linked (fructose, trehalose)
Disaccharide nomenclature • Nonreducing end on left • Linkage –(nm)- • Reducing end Note that nonreducing end configuration is fixed Reducing end can mutarotate, thus 1st component given as - or -, 2nd ambiguous (next slide)
Important disaccharides • Maltose • Lactose • Sucrose • Trehalose
Storage polysaccharides • Plants • Starch • Amylose – llinear polyglucose, -1,4 linked (-D-glucopyranosyl-(14)-…), 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
Fig 9-14 0.10 m 1.0 m
Structural Polysaccharides • Plants • Cellulose – linear polyglucose • 1,4 linked • M ~ 106 • Certain exoskeletons • Chitin – linear poly(N-acetyl-D-glucosamine) • 1,4 linked
Fig 9-17a and 9-18 Cellulose Chitin
Structural polysaccharides, cont • Bacterial cell walls – peptidoglycans • Extracellular matrix of multicellular animals - glycosaminoglycans
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)