Premium
SYNAPTOSOMAL PHOSPHORYLATION OF D‐GLUCOSAMINE
Author(s) -
Tan C. H.,
Raghupathy E.,
Peterson N. A.
Publication year - 1978
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1978.tb02664.x
Subject(s) - phosphorylation , glucosamine , d glucosamine , chemistry , biochemistry , sugar phosphates , phosphate , protein phosphorylation , protein kinase a
— Synaptosomal fractions from rat brains can phosphorylate d ‐glucosamine once it is transported across the synaptosomal membrane. Intrasynaptosomal phosphorylation of d ‐glucosamine was rapid; up to 80% of the d ‐glucosamine was recovered as the phosphorylated amino sugar during 15 min of incubation with the substrate. Transport of d ‐glucosamine was the rate‐limiting step in the uptake process since in the presence of cytochalasin B, a specific sugar transport inhibitor, the uptake of d ‐glucosamine was inhibited to the same extent as its phosphorylation. The pH optimum for phosphorylation of d ‐glucosamine by lysed synaptosomal preparations was between 7.5 and 9.0. The mean K m and V max values for this phosphorylation were 0.46 DIM and 676 nmol/mg protein per min, respectively. Phosphorylation of d ‐glucosamine was inhibited competitively by d ‐glucose, 2‐deoxy‐ d ‐glucose and N ‐acetyl‐ d ‐glucosamine and uncompetitively by d ‐glucose‐6‐phosphate. The phosphorylation was strongly inhibited by several sulfhydryl reagents, but was insensitive to product inhibition, cytochalasin B, phloretin and phloridzin.