Ch. 7 Carbs and Glycoconjugates - The Molecules
D-Galactose
(Gal) Aldohexose 3rd & 4th Carbons -OH on left
D-Glucose
(Glc) Aldohexose 3rd Carbon -OH on left
D-Mannose
(Man) Aldohexose 2nd & 3rd Carbons -OH on left
D-Ribose
(Rib) Aldopentose
Aldoses
According to convention, the d- and l-forms of a monosaccharide are mirror images of each other, as shown in Figure 7.4 for fructose. Stereoisomers that are mirror images of each other are called enantiomers, or sometimes enantiomeric pairs. For molecules that possess two or more chiral centers, more than two stereoisomers can exist. Pairs of isomers that have opposite configurations at one or more of the chiral centers but that are not mirror images of each other are called diastereomers or diastereomeric pairs. Any two structures in a given row in Figures 7.2 and 7.3 are diastereomeric pairs. Two sugars that differ in configuration at only one chiral center are described as epimers. For example, d-mannose and d-talose are epimers and d-glucose and d-mannose are epimers, whereas d-glucose and d-talose are not epimers but merely diastereomers.
D-Erythrose
Aldotetrose
D-Glyceraldehyde
Aldotriose
Chondroitin-4-sulfate
Glycosaminoglycans
Chondroitin-6-sulfate
Glycosaminoglycans
Dermatan sulfate
Glycosaminoglycans
Heparin
Glycosaminoglycans
Hyaluronate
Glycosaminoglycans
Keratan sulfate
Glycosaminoglycans
Sedulose
Heptose
D-Fructose
Ketohexose 3rd Carbon -OH on left
D-Ribulose
Ketopentose
Dihydroxyacetone
Ketotriose
Ketoses
Most common Ketoses shown in Blue
Glycoproteins: N-Linkage between Carbohydrates and Proteins
N-Linked Oligosaccharides
Glycoproteins: O-Linkage between Carbohydrates and Proteins
O-Linked Oligosaccharides
2-Deoxy-α-D-ribose
Pentose The deoxy sugars are monosaccharides with one or more hydroxyl groups replaced by hydrogens.
Amylopectin
Polysaccharide
Amylose
Polysaccharide
Cellulose
Polysaccharide
Chitin
Polysaccharide
Dextran
Polysaccharide Dextrans are a(1 8n 6)-linked polysaccharides of d-glucose with branched chains found in yeast and bacteria. Because the main polymer chain is a(1 8n 6) linked, the repeating unit is isomaltose, Glca1 8n 6Glc. The branch points may be 1 8n 2, 1 8n 3, or 1 8n 4 in various species. The degree of branching and the average chain length between branches depend on the species and strain of the organism. Bacteria growing on the surfaces of teeth produce extracellular accumulations of dextrans, an important component of dental plaque.
Glycogen
Polysaccharide Liver glycogen consists of granules containing highly branched molecules, with a(1 8n 6) branches occurring every 8 to 12 glucose units. Like amylopectin, glycogen yields a red-violet color with iodine. Glycogen can be hydrolyzed by both a- and b-amylases, yielding glucose and maltose, respectively, as products and can also be hydrolyzed by glycogen phosphorylase, an enzyme present in liver and muscle tissue, to release glucose-1-phosphate.
Lactose
galactose-β-1,4-glucose Disaccharide pink hexose = glucose yellow hexose = galactose blue pentose = fructose
Maltose
glucose-α-1,4-glucose Disaccharide pink hexose = glucose yellow hexose = galactose blue pentose = fructose
Isomaltose
glucose-α-1,6-glucose Disaccharide pink hexose = glucose yellow hexose = galactose blue pentose = fructose
Sucrose
glucose-α1-β2-fructose Disaccharide pink hexose = glucose yellow hexose = galactose blue pentose = fructose
Cellobiose
glucose-β-1,4-glucose Disaccharide pink hexose = glucose yellow hexose = galactose blue pentose = fructose
