Dissimilar effects of D-mannoheptulose on the phosphorylation of α- versus β-D-glucose by either hexokinase or glucokinase
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- Published online on: October 1, 2004 https://doi.org/10.3892/ijmm.14.1.107
- Pages: 107-112
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Abstract
D-mannoheptulose inhibits D-glucose phosphorylation by hexokinase isoenzymes. The present study aims at investigating whether the pattern of such an inhibition differs in the case of α- versus β-D-glucose. The phosphorylation of α- and β-D-[U-14C]glucose was measured over 60-min incubation at 4°C in the presence of bovine heart hexokinase and over 10 min at 24°C in the presence of human liver glucokinase. The relative extent of the inhibitory action of D-mannoheptulose (0.02-10.0 mM) was always less marked with α- than β-D-glucose. In the case of hexokinase, the experiments conducted at the high concentration of the D-glucose anomers (1.0 mM) revealed that D-mannoheptulose, at low concentrations (0.2-0.5 mM), may unexpectedly increase the phosphorylation of α-D-glucose. These findings thus document anomeric specificity in terms of the inhibitory action of D-mannoheptulose upon α- versus β-D-glucose phosphorylation by either hexokinase or glucokinase.