The mechanism of the reversible aerobic inhibition of glycolysis in a pea-seed extract

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Abstract
Processes responsible for the oxidation of sulphydryl groups and the reduction of disulphide groups of glyceraldehyde 3-phosphate dehydrogenase in a pea-seed extract were examined. The inhibition of glyceraldehyde 3-phosphate dehydrogenase in aerobic glycolytic digests was due to the oxidation of the essential sulphydryl groups of the enzyme. Evidence indicated that the oxidation of protein sulphydryl groups may have been a non-enzymic process catalyzed by traces of heavy metals. Reduction of protein disulphide groups in the pea-seed extract occurred in the presence of reduced diphosphopyridine nucleotide or of systems which generated reduced di- or tri-phosphopyridine nucleotide. Under these conditions glyceraldehyde 3-phosphate dehydrogenase in the extract was activated. In the presence of reduced diphosphopyridine nucleotide and a heat-labile component of the pea-seed extract, enzyme activity and the protein sulphydryl group concentration of pea-seed glyceraldehyde 3-phosphate dehydrogenase preparation were increased. It is suggested that aerobic glycolytic activity in the pea-seed extract was controlled by processes which mediated the oxidation of sulphydryl groups and the reduction of disulphide groups of glyceraldehyde 3-phosphate dehydrogenase.