92 PHYSIOLOGY OF YEASTS 



sist boiling temperatures. The investigations of Buchner, 1 Hoffman, 

 Duchacek, 1 Klatte, 2 Hoehn 3 and Resenbeck have confirmed the exist- 

 ence of a coferment. In adding this yeast juice to a double vol- 

 ume of boiled juice these investigators have noticed an increase in the 

 activity, almost proportional to the amount of boiled juice added. 

 On the other hand the addition of inactive boiled juice to the yeast 

 juice, which had become inactive, restored the fermenting activity. 

 This demonstrated that in old juice there is active zymase but that 

 it lacks a coferment. This coferment seems, then, to disappear during 

 fermentation before the zymase. Gromow and Grigoriew have also 

 reported that if fresh zymase is added to a zymase which is becoming 

 inactive, more fermentation is secured than if the fresh zymase was 

 used alone. The old zymase has ceased to act on acccount of the al- 

 teration of its coferment and the addition of the fresh zymase regen- 

 erates it. 



From all of this has been established that zymase may result from 

 a mixture of two substances: a dialyzable body which resists boiling, 

 the coferment, and a substance little or not dialyzable, which does 

 not resist boiling. It is only by the union of the two bodies that 

 fermentation takes place. 



The investigations of Wroblewsky, Buchner, Harden and Young 

 have permitted some explanations of the nature of the coferment. 

 These authors have stated that the addition of phosphate salts of 

 sodium or potassium will, like the ferment, produce an accelera- 

 tion in fermentation. The addition of serum or lecithin produces 

 the same effect. The coferment loses its activity by heating for 4 

 hours in water at 130 C. It is not attacked by trypsin but is destroyed 

 by the lipase which exists in the yeast juice. The action of this lip- 

 ase in the yeast juice seems then to be, with the endotryptase, the 

 principal cause of the rapid loss of zymase activity. The lipase 

 acts on the coferment and the endotryptase on the zymase. The 

 coferment is present in lesser quantities than the zymase. It is able 

 to be kept in sugar. This represses the action of proteolytic enzymes 

 and perhaps the lipase. In this way, the action of these strong sugar 

 solutions may be explained. Later on all these facts will be of much 

 interest in the discussion of the mechanism of the alcoholic fermen- 

 tation. 



1 Buchner, E. and Duchacek, E. Ueber fraktionierte Fallung des Hefe- 

 pressaftes. Biochem. Zeitschr. 15, 1909. 



2 Buchner, E. and Klatte, F. Ueber das Koenzym in Hefepressaft. Biochem. 

 Zeitschr. 19, 1909. 



3 Buchner, E. and Hoehn, H. Ueber das Spiel der Enzyme in Hefepressaft. 

 Biochem. Zeitschr. 19, 1909. 



