Abstract
Human B-cell glucokinase displays sigmoidal kinetics towards D-glucose or D-mannose, but fails to do so towards D-fructose. Yet, D-glucose, D-mannose and 2-deoxy-D-glucose confer to the enzyme positive cooperativity towards D-fructose. For instance, in the presence of 5 mM D-[U-14C]fructose, its rate of phosphorylation is increased to 214.3 ± 11.0%, 134.0 ± 4.3% and 116.5 ± 3.0% of paired control value by D-glucose, D-mannose and 2-deoxy-D-glucose (each 6 mM), respectively. D-glucose and, to a lesser extent, D-mannose also display reciprocal kinetic cooperativity. D-fructose, however, fails to affect D-glucose or D-mannose phosphorylation under conditions in which positive cooperativity is otherwise observed. These findings are relevant to the reciprocal effects of distinct hexoses upon their phosphorylation by B-cell glucokinase and, as such, to the metabolic and functional response evoked in pancreatic islet B-cells by these sugars, when tested either separately or in combination. (Mol Cell Biochem 175: 263–269, 1997)
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Scruel, O., Sener, A. & Malaisse, W.J. Glucose-induced positive cooperativity of fructose phosphorylation by human B-cell glucokinase. Mol Cell Biochem 175, 263–269 (1997). https://doi.org/10.1023/A:1006834010660
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DOI: https://doi.org/10.1023/A:1006834010660