ENZYMIG REGULATION OF FERMENTATION 

 IN YEAST CELLS 



Helmut Holzer 



Physiologisch-Chemisches Institut der Universitat, Freiburg im Breisgau 



The analysis of the changes of metaboHte concentrations 

 which take place during the transition from one metabolic 

 situation to another should give an insight into the co-opera- 

 tion of enzymes in living cells (Holzer, 1953, 1956). The 

 following is a report on some results of the study of the 

 co-operation of fermentative enzymes in living yeast cells by 

 means of this method. 



Regulation of fermentation rate by oxidation of 

 reduced diphosphopyridine nucleotide 



Only very low, barely demonstrable, concentrations of 

 intermediates of carbohydrate metabolism can be found in 

 yeast cells which have been starved by shaking with oxygen. 

 If glucose is added to these starved yeast cells under aerobic 

 or anaerobic conditions, then — almost without induction 

 time — an intensive degradation of glucose commences, and 

 readily measurable concentrations of carbohydrate meta- 

 bolites are observed. We analysed such concentrations during 

 the transition from the resting (starved) state to the stationary 

 glucose-decomposing state (Holzer and Freytag-Hilf, 1959). 



Fig. 1 shows the changes in fructose diphosphate concen- 

 tration after the addition of glucose to starved yeast cells. 

 Under aerobic and anaerobic conditions a characteristic 

 "Einpendeln" of the fructose ^diphosphate concentration is 

 observed (Holzer, 1956). Without doubt the occurrence of a 

 maximum results from a change in the quotient : 



production rate of the metabolite in question 



Q 



consumption rate of the metabolite in question 



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