Reciprocal Influence of Glucose Anomers upon their Respective Phosphorylation by Hexokinase

Publisher Website
Google Scholar
Abstract
The phosphorylation of D-glucose (1.0 mM) was measured in homogenates of tumoral islet cells incubated at 7.degree. C in the presence of labelled .alpha.- and/or .beta.-D-glucose, with or without exogenous glucose 6-phosphate. The close-to-maximal reaction velocity of hexokinase was higher with .beta.- and .alpha.-D-glucose. The latter anomer inhibited .beta.-D-glucose phosphorylation more than the .beta.-anomer decreased the phosphorylation of .alpha.-D-glucose. This behaviour was accounted for by the higher affinity of hexokinase for .alpha.- than for .beta.-D-glucose. Thes direct measurements of the relative contribution of each anomer to the overall rate of glucose phosphorylation in the presence of mixed populations of .alpha.- and .beta.-D-glucose validate the concept that the phosphorylation of D-glucose displays anomeric specificity even when the hexose is used at anomeric equilibrium. Glucose 6-phosphate inhibited the phosphorylation of the two anomers more severely when .alpha.-D-glucose rather than .beta.-D-glucose was the most abundant anomer.

This publication has 4 references indexed in Scilit: