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Studies on the regulation of enolases and compartmentation of cytosolic enzymes in Saccharomyces cerevisiae

1987; Elsevier BV; Volume: 923; Issue: 2 Linguagem: Inglês

10.1016/0304-4165(87)90006-7

1872-8006

Karl‐Dieter Entian, Bernd Meurer, Köhler Helmut, Karlheinz Mann, Dieter Mecke,

Cancer, Hypoxia, and Metabolism

Three enolase isoenzymes can be distinguised after electrophoresis of yeast crude extracts. After adding glucose to derepressed cells, there was a coordinated increase in the activity of enolase I and decrease in enolase II activity. Enolase I was found to be repressed and enolase II simultaneously induced glucose. The third enolase activity remained unchanged and was identified as that of a hybrid enzyme. Enolase catalyses the first common step of glycolysis and gluconeogenesis. Gluconeogenic enolase I shows substrate inhibition for 2-phosphoglycerate (glycolytic substrate) and glycolytic enolase II is substrate-inhibited by phosphoenolpyruvate (gluconeogenic substrate). The gluconeogenic reaction was inhibited up to 45% by physiological concentrations of fructose 1,6-bisphosphate. To test for cytological compartmentation, a method was developed for isolating microsomes. Effective enrichment of rough and smooth endoplasmic reticulum was demonstrated by electron microscopy. No evidence was obtained for any compartmentation of either enolases or other glycolytic enzymes.