Comparative Studies on the Purification of Tetanus and Diphtheria Toxins

Abstract

A simplified method for the purification of diphtheria and tetanus toxins by precipitation with cadmium chloride is described. Preparations of the two toxins purified to about the same degree (separation of over 99 per cent of nitrogenous impurities) differ in the proportions of protein nitrogen present. The purified tetanus toxin contained only 8 to 18 per cent of protein nitrogen while the diphtheria toxin was practically all protein. Unlike diphtheria toxin purified tetanus toxin is not precipitable by acid or alum. The findings indicate that tetanus toxin differs from diphtheria toxin in lacking some of the chemical properties commonly attributed to a typical protein.