Fundamentals of
Biochemistry
Third Edition
Donald Voet • Judith G. Voet •
Charlotte W. Pratt
Chapter 8
Carbohydrates
Copyright © 2008 by John Wiley & Sons, Inc.
Section1 – Monosaccharides
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Monosaccharide
Polysaccharide
Aldose
Ketose
Chiral Carbons 2n
This reaction happens freely (slowly) in solution: 64% beta, 36% alpha
Preferred
Oxidation of aldehyde
-onic acid
Oxidation of primary
alcohol
-uronic acid
Mild conditions, reduction to polyhydroxy alcohols
-itol added to most names
Amino sugars – add amino group in place of -OH
Sialic acids are important for glycoproteins and glycolipids;
recognition site of Influenza Viruses
Glycosidic bonds – reaction of anomeric group to an alcohol
Reducing
Non-Reducing
Section 2 – Polysaccharides
O-β-D-galactopyranosyl(1→4)-D-glucopyranose
O-α-D-glucopyranosyl-(1→2)β-D-fructofuranoside
Sucralose
(Splenda)
Steviol
(Stevia)
Sodium
cyclamate
β(1→4) linkages
Cannot be broken down
in vertebrate digestion
Exoskeletons
α(1→4) linkages
Energy Storage in plants
1 every 24-30 units
Digestion:
amylase
α-glucosidase
debranching enzymes
glycogen debranching enzyme
Glycogen has more
branch points than
amylopetin (1 every 814 units
Figure 8-12
Section 3 - Glycoproteins
N-linked oligosaccharides
O-linked oligosaccharides
Biological Activity
• Define protein structure
– Usually on surface
– limit conformation; stabilize fold
• Recognition
– Glycoconjugates
• Lectins – identify specific oligosaccharides
• Selectins – attachment of leukocytes
– Blood groups
All chapter questions