Activity of glycolytic enzymes of Saccharomyces cerevisiae in the presence of acetic acid

Summary The effect of acetic acid on transport of glucose and on the activity of glycolytic enzymes of Saccharomyces cerevisiae was investigated. Acetic acid did not affect glucose transport. The inhibitory effect of the acid on the enzymes was considered from the point of view of acidification of the cytoplasm (pH dependence of the activity) and of the direct effect of the presence of acetic acid. Enolase was the enzyme most severely affected according to these two criteria. Fermentation was monitored in vivo by ³¹P-NMR. When ATP was available, a rise in cytoplasmic pH was observed and fermentation proceeded with a lower level of sugar phosphate. This may indicate that control was exerted at one of the early phosphorylation steps.Offprint requests to: M. C. Loureiro-Dias