Open AccessTransglycosylic Reactions of Deoxysugars
Author(s) -
ZEMEK Jiřì,
KUČÁR Štefan,
ZÁMOCKÝ Juraj
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb20926.x
Subject(s) - chemistry , starch , glucan , stereochemistry , residue (chemistry) , glycogen phosphorylase , biosynthesis , moiety , phosphate , biochemistry , carbohydrate , enzyme
The biosynthesis of starch was investigated in the reaction catalyzed by plant α(1→4)‐glucan phosphorylase using α‐ d ‐glucopyranosyl phosphate and its deoxy analogues as substrates. It was found that the hydroxyl groups at the positions C‐2, C‐3, C‐4 and C‐6 in the glucose moiety of the molecule of α‐ d ‐glucopyranosyl phosphate are not essential for its substrate properties in the transglycosylic reaction. The affinity of plant α(1→4)‐glucan phosphorylase and the rate of hexose incorporation into α(1→4)‐glucan decreases in the following sequence: α‐ d ‐glucopyranosyl phosphosphate, 2‐deoxy‐, 6‐deoxy, 4‐deoxy, and 3‐deoxy‐α‐ d ‐glucopyranosyl phosphate. The deoxyglucosyl analogues of α‐ d ‐glucosylpyranosyl phosphate act as competitive inhibitors on the elongation reaction of the α(1→4) chains of starch. It was found that more than one residue of 2‐deoxy‐ d ‐glucose or 6‐deoxy‐ d ‐glucose can be incorporated into the nonreducing terminus of α(1→4)‐glucan chains of starch.