On the probable existence of emulsin in yeast

Abstract

The observations of Treub, Greshoff, Jouck, and other investigators have established the fact that hydrocyanic acid is furnished by a comparatively large number of plants belonging to a wide range of natural orders. Dunstan and Henry have applied to this process the name “cyanogenesis,” and have shown that in many plants the production of hydrocyanic acid is due to the interaction of a cyanogenetic glucoside with a specific enzyme. Thus in Lotus arabicus , the hydrocyanic acid is produced by the decomposition of the glucoside lotusin by the enzyme lotase, in Sorghum vulgare by the action of emulsin on the glucoside dhurrin, and in the seeds of Phoseolus lunatus as the result of the decomposition of phaseolunatin by the enzyme emulsin. The same authors have indicated that similar actions probably take place in cassava ( Manihot utilissim ), Lotus australis and Chailletia cymosa , all of which have been found to yield hydrocyanic acid when crushed in presence of water. The isolation of these cyanogenetic glucosides is often a matter of considerable difficulty, because, as a rule, they are only soluble in water and aqueous alcohol, and it is therefore a troublesome operation to separate them from the associated sugar (usually dextrose) and pectous matter which are also, in general, only soluble in the same solvents. In a few cases it has been found possible to remove dextrose from such mixtures by the action of phenylhydrazine, but this process usually leads to the loss of a portion of the glucoside, owing to partial condensation with the reagent. Some cyanogenetic glucosides are also slightly soluble in ethyl acetate, and this solvent has been employed for the isolation of mandelonitrile glucoside and of dhurrin and phaseolunatin.