High glucose concentrations partially release hexokinase from inhibition by glucose 6-phosphate.

High glucose concentrations partially release hexokinase from inhibition by glucose 6-phosphate.

The phosphorylation of glucose by human erythrocyte hexokinase follows classical Michaelis-Menten kinetics; hexokinase manifests maximum activity at 5 mM glucose, and no further increase in activity can be measured at higher glucose concentrations. However, the erythrocytes of diabetics and normal erythrocytes incubated with high concentrations of glucose contain increased concentrations of glu...

Allosteric character of the inhibition of rat-muscle hexokinase B by glucose 6-phosphate.

We previously provided evidence from isotope-exchange measurements under non-equilibrium conditions that hexokinase B from rat muscle follows a compulsory-order mechanism with glucose binding before MgATP, and with both glucose 6-phosphate and MgATP capable of binding allosterically [Gregoriou, M., Trayer, I. P. & Cornish-Bowden, A. (1983) Eur. J. Biochem. 134, 283-288]. We have now re-examined...

Inhibition of Human Erythrocyte Glucose 6-Phosphate Dehydrogenase by Cadmium, Nickel and Aluminium

INHIBITION OF HUMAN ERYTHROCYTE GLUCOSE 6-PHOSPHATE DEHYDROGENASE ACTIVITY BY DEHYDROEPIANDROSTERONE AND RELATED STEROIDS.

The inhibitory effects of several steroids on G6PD activity using intact erythrocytes are reported. Incubation of whole blood with dehydroepiandrosterone (DHEA) resulted in 42% and 12% inhibition in the enzyme activity in the presence and absence of oxygen, respectively. Addition of epinephrine and/or aminophylline into the incubation medium caused further enzyme inhibition suggesting a po...

Kinetic 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...