The inhibition of hexokinase by disulphides

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Abstract
The effects of disulphides on glucose utilization in various rat tissues in vitro as well as on crude calf-brain hexokinase have been studied. High concentrations of disulphides inhibit the utilization of glucose in diaphragm, brain, testicle, and kidney, whereas the production of lactic acid from endogenous substrates is not inhibited. Crude calf-brain hexokinase is inhibited by disulphides to the same extent as is the utilization of glucose in brain-tissue slices. Both inhibitions can be partially reversed by thiols. The inhibition is tentatively ascribed to mixed disulphide formation on essential thiol groups of hexokinase. Glucose and to a limited extent the adenosine triphosphate-Mg2++ ion complex protect crude calf-brain hexokinase against the inhibition by disulphides. The apparent specificity of the enzyme inhibitory action of disulphides of low oxidation-reduction potentials, as well as the protective mechanism of the cells against this inhibition, are discussed.