226 P. P. Slonimski and H. de Robichon-Szulmajster 



structure of the chondriome and of the perinuclear zone 

 (Ephrussi et ah, 1956). 



If yeast is taken from the glucose fermentation phase it will 

 rapidly adapt to maltose. If it is taken from the ethanol phase 

 no maltozymase is formed. 



In such cells an addition of E produces a dramatic effect, 

 restoring completely the maltozymase adaptation (Fig. 4). 

 Cofactor E does not act as a cofactor of maltozymase function, 

 as is shown by the following experiments. 



300 



200 



100 



Q, 



C02ferm 



CONTROL, GLUCOSE 



-o — -^; — -n — — , , , a - »e 



<< HRS 8 



Fig. 4. Effect of commercial erythrose (0 • 5 

 mg./ml.) or glucose (0-5 mg./ml.) on malto- 

 zymase adaptation. 

 Adaptation in aerated plios. pht. succ. buffer 

 containing 10 mg. maltose /ml. 



Firstly, addition of E does not provoke an immediate 

 fermentation of maltose but only permits adaptation to occur. 

 Depending on the amount of E added at zero time, adaptation 

 takes place more or less rapidly, but even with saturating 

 concentrations of E the half-maximal rate of fermentation of 

 maltose is attained only after ca. 3 hours. Secondly, addition 

 of E six hours after the addition of maltose in excess does not 

 bring about an immediate fermentation. This last experiment 

 is of critical importance. If cofactor E were involved in 

 permitting the expression of the maltozymase function, its 



