369 



The Alcoholic Ferment of Yeast-juice. Part II. — The C of er merit 



of Yeast-juice. 



By Arthur Hakden, D.Sc, Ph.D., and William Johx Young, M.Sc. 



(Communicated by Dr. C. J. Martin, F.R.S. Eeceived June 14, — Read June 28, 



1906.) 



(From the Chemical Laboratory, Lister Institute.) 



In a previous communication* it was shown that the fermentation of 

 glucose by yeast-juice is dependent upon the presence of a dialysable 

 substance which is not destroyed by heat. This substance is contained in 

 the active yeast-juice prepared by disintegrating living yeast, and, therefore, 

 most probably exists in the yeast cell side by side with the zymase. 



The occurrence of an analogous activating substance has been described 

 by Magnusf in the case of the lipase of the liver. He observed that the 

 active juice of this organ became inactive when dialysed into water, but 

 regained its activity when the dialysate or boiled liver juice was added. 

 The term coferment was suggested by BertrandJ to denote substances of 

 this kind, and he applied it in two instances — to the calcium salt, which 

 he considered was necessary for the action of pectase on pecten substances, 

 and to the manganese of laccase. which he supposed to be essential for the 

 activity of this enzyme. Although not entirely satisfactory, this term may 

 be provisionally applied to activating substances such as those present in 

 liver lipase and yeast-juice, until further knowledge of their nature and 

 function permits of a more rational terminology. 



(1) Preparation of the Inactive Residue f rom Yeast-juice in the Dry State. 



In the previous communication § it was shown that when yeast-juice is 

 filtered through a Martin gelatin filter, both the residue and the filtrate are 

 incapable of fermenting sugar, whereas a mixture of the two produces a 

 vigorous fermentation. 



In carrying out the experiments which established this result, the residue 

 left on the filter was always dissolved in water as soon as the filtration and 

 washing were completed, and the activity of the solution was examined 

 without delay. It has since been found possible to obtain the inactive 



* 'Roy. Soe. Proe.,' B, vol. 77, 1906, p. 410. 

 t ' Zeit. Physiol. Chem.,' 1904, vol. 42, p. 149. 

 | 1 Compt. Rend.,' 1897, vol. 124, p. 1032. 

 § Loc. cit. 



