The alcoholic ferment of yeast-juice. Part II.—The coferment of yeast-juice

Abstract

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 Magnus 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 Bertrand 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.