Action of nitrogen trichloride on certain proteins I. Isolation and identification of the toxic factor

When proteins in which the content of methionine is relatively high are treated with nitrogen trichloride they become toxic to certain animals. This effect is observed, for example, with zein, gluten and egg albumen. If these treated proteins are digested, either enzymatically or by partial acid hydrolysis, the toxic property persists in the hydrolysates. Methods are described by which such hydrolysates have been fractionated, and the toxic component isolated as a pure crystalline substance. The toxic factor derived from each of the three proteins, zein, gluten and egg albumen, is found to be the same chemical substance. Data are given which establish that it is a derivative of the amino-acid methionine with the molecular formula C5H12N2O3S, and the structural formula HOOCCHCH2CH2 O̅ | ⁄ NH2 S++ ⁄ CH3 NH- This molecule exhibits diastereo-isomerism, and it is probable that the various isomers have differing biological activity.