Comparative Studies on the Purification of Tetanus and Diphtheria Toxins.

Diphtheria toxin has been identified as a typical heat-coagulable protein (Eaton 1936 a, 1937; Pappenheimer 1937). If other toxins have chemical properties similar to diphtheria toxin, they might be isolated by similar methods. Using a gelatin hydrolysate medium, Pappenheimer and Johnson (1936, 1937) have produced diphtheria toxin which may be obtained in a relatively pure state by simple fractionation with ammonium sulphate. However, strong tetanus toxin has not been produced on a simplified medium similar to that used by Pappenheimer and Johnson for diphtheria toxin. Consequently, attempts to isolate tetanus toxin must be confined, at present, to the separation of the toxin from the proteins, proteoses, and peptones of the usual complex media. The method of purifying toxins by precipitation with alum and cadmium chloride, as previously described (Eaton 1936 a, b), has been simplified by omitting the precipitation with alum and by making certain other modifications. Diphtheria toxin made on the proteose-peptone medium of Wadsworth and Wheeler (1934) and tetanus toxin, made on a meat infusion medium, may be considerably purified without appreciable alteration by a single precipitation with cadmium chloride. For the purpose of comparing the properties of diphtheria and tetanus toxins, the toxins must be made on similar media and purified by similar methods unless the complete purity of the final products can be proved. Differences in the properties of the two toxins necessitate the use of slightly different methods