Page 49 - Academic Press Encyclopedia of Physical Science and Technology 3rd BioChemistry

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Encyclopedia of Physical Science and Technology EN006P-81 June 29, 2001 21:48

Glycoconjugates and

Carbohydrates

Eugene A. Davidson

Georgetown University School of Medicine

I. Monosaccharides
II. Oligosaccharides
III. Polysaccharides
IV. Glycoconjugates
V. Analytical Methods

GLOSSARY a single asymmetric center. Thus, D-galactose is the
4-epimer of D-glucose.
Aglycone Group attached to the hydroxyl of a furanose Furanose Five-membered ring (derived from furan) with
or pyranose sugar to form a glycoside. Can vary from a single oxygen formed by reaction of the carbonyl
a simple methyl group to other sugars to complex carbon of an aldose or ketose with the appropriate hy-
alkaloids. droxyl group. Sugars commonly found as furanoses
Aldose Polyhydroxy aldehyde with three or more car- include ribose and 2-deoxyribose (in RNA and DNA,
bon atoms. When of sufficient length will form five- respectively), and fructose in combined form (sucrose,
or six-membered ring (furanose or pyranose) hemiac- for example).
etals. Designated D-or L- based on the configuration of Glycolipid Structure containing one or more saccharide
the asymmetric center furthest from the carbonyl group units covalently attached to the primary hydroxyl group
relative to glyceraldehyde. of N-acyl sphingosine (ceramide), a C-18 amino alco-
Anomer Formation of the cyclic ring structure confers hol. Those containing sialic acid are termed ganglio-
asymmetry on the original carbonyl carbon atom. The sides.
two anomers produced are alpha- (the newly formed Glycoprotein Protein with covalently attached saccha-
hydroxyl group projects on the same side as the five- or rides. Linkage may be N- (amide nitrogen of aspara-
six-membered ring) or beta- (the new hydroxyl projects gine residues), or O- (serine and threonine are most
on the opposite side of the newly formed ring). This common). The saccharide units may be heterogeneous
is combined with D-, or L-; α-D-glucopyranose, β-L- within the same protein, even at the identical substitu-
fructofuranose, for example. tion site.
Epimer Saccharide that differs from a reference sugar at Glycosaminoglycan Polysaccharide chain found in

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