Oscillatory reductions of pyridine nucleotides during anaerobic glycolysis in brewers' yeast

Abstract

Measurement of the kinetics of pyridine nucleotides during anaerobic glycolysis in a strain of Saccharomyces carlsbergensis by fluorometric or spectrophotometric techniques has revealed an oscillatory approach to a steady state in reduced pyridine nucleotides. This oscillatory approach is strongly dependent on the initial glucose concentration. Preincubation with ethanol abolishes these cyclic responses of pyridine nucleotides unless glucose is added after sufficient time has elapsed after attainment of anaerobiosis by ethanol oxidation. 2-Deoxy- d-glucose can induce oscillatory reductions of pyridine nucleotides. Analysis of glycolytic intermediates and adenine nucleotides revealed ADP, phosphoenol pyruvate, and fructose-1,6-diphosphate to be in phase with reduced pyridine nucleotide; in phase with the oxidized form of pyridine nucleotide were glucose-6-phosphate, 3-phosphoglyceraldehyde, pyruvate, and acetaldehyde. These phenomena can in part be explained by ADP control, either by participation of ADP in the triosephosphate dehydrogenase reaction or via activation of phosphofructokinase. Under the conditions where the oscillatory approach to a steady state in reduced pyridine nucleotides is observed in this yeast, inorganic phosphate is not rate limiting, as experiments with deoxyglucose have demonstrated.