Physiological Effects of Seven Different Blocks in Glycolysis in Saccharomyces cerevisiae

摘要: Saccharomyces cerevisiae mutants unable to grow and ferment glucose have been isolated. Of 45 clones isolated, 25 had single enzyme defects of one the following activities: phosphoglucose isomerase (pgi), phosphofructokinase (pfk), triosephosphate (tpi), phosphoglycerate kinase (pgk), phosphoglyceromutase (pgm), pyruvate (pyk). Phosphofructokinase activities in crude extracts pfk mutant were only 2% wild-type level. However, normal growth on medium fermentation suggested either that was considerably more active vivo or, alternatively, residual activity sufficient for glycolysis. All other moderately strongly inhibited by glucose. Unusually high concentrations glycolytic metabolites observed before reaction catalyzed which absent a given strain when incubated This confirmed at cellular level location defect as determined assays. With adh (lacks all three alcohol dehydrogenase isozymes) pgk mutants, accumulation typical levels hexosephosphates prevented respiration blocked with antimycin A. A feature described here rapid depletion intracellular adenosine 5′-triphosphate pool after transfer medium. No correlation low or fructose-1,6-bisphosphate degree catabolite repression inactivation could be found. observation does not support concept hexose are directly involved these regulatory mechanisms yeast.