Kinetics of hexokinase D (‘glucokinase’) with inosine triphosphate as phosphate donor. Loss of kinetic co-operativity with respect to glucose
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Kinetics of hexokinase D ('glucokinase') with inosine triphosphate as phosphate donor. Loss of kinetic co-operativity with respect to glucose.
When ATP, the normal phosphate donor for hexokinase D ('glucokinase'), is replaced by ITP, the positive co-operativity with respect to glucose disappears. This may be rationalized in relation to kinetic models for hexokinase D co-operativity, which assume that with the normal substrates the chemical reaction and subsequent release of products occur so rapidly that binding of substrates cannot a...
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The kinetic mechanism of rat liver hexokinase D ('glucokinase') was studied under non-co-operative conditions with 2-deoxyglucose as substrate, chosen to avoid uncertainties derived from the co-operativity observed with the physiological substrate, glucose. The enzyme shows hyperbolic kinetics with respect to both 2-deoxyglucose and MgATP(2-), and the reaction follows a ternary-complex mechanis...
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Hexokinase D ('glucokinase') displays positive cooperativity with mannose with the same h values (1.5-1.6) as with glucose but with higher K0.5 values (8 mM at pH 8.0 and 12 mM at pH 7.5). In contrast, fructose and 2-deoxyglucose exhibit Michaelian kinetics [Cárdenas, M. L., Rabajille, E., and Niemeyer, H. (1979) Arch. Biol. Med. Exp. 12, 571-580; Cárdenas, M. L., Rabajille, E., and Niemeyer, H...
متن کاملKinetic determination of serum glucose by use of the hexokinase/glucose-6-phosphate dehydrogenase method.
We have developed a kinetic fixed-time approach for the quantitative determination of serum glucose by use of the hexokinase/glucose-6-phosphate dehydrogenase method. To achieve a large measuring range, we have apparently increased the Michaelis constant of glucose-6-phosphate dehydrogenase through addition of the competitive inhibitor ATP. By this means, serum samples with glucose concentratio...
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ژورنال
عنوان ژورنال: Biochemical Journal
سال: 1987
ISSN: 0264-6021,1470-8728
DOI: 10.1042/bj2450625