Study of the Feedback Effect of Ethanol on Selected Enzymes of the Glycolytic Pathway

Abstract

The effect of ethanol on the regulation of the glycolytic pathway was investigated. A reversible enzyme-inhibitor complex is suggested as the cause of difficulties in demonstrating ethanol feedback inhibition of specific enzymes. The assay procedures for the enzymes hexokinase and phosphofructokinase were modified by adjusting the reaction mixtures as well as the enzyme preparations to specific ethanol concentrations. Noncompetitive feedback inhibition by ethanol of the enzymes hexokinase and alpha-glycerophosphate dehydrogenase was detected. A scheme suggesting noncompetitive feedback inhibition, by ethano), first of the enzyme alpha-glycerophosphate dehydrogenase and second of the enzyme hexokinase, is presented to partially explain the regulation of glycerol and ethanol production in the yeast cell.