Crystalline ɛ-Prototoxin from Clostridium welchii

Abstract

IT has long been known that the lethal and necrotic ɛ-toxin of Clostridium welchii occurs in cultures as a non-toxic precursor¹. Turner and Rodwell² showed that the toxicity of culture filtrates could be potentiated by incubation with trypsin and certain bacterial proteases. They defined the activation ratio of an ɛ-antigen fraction as the ratio of the LD₁₀₀ in mice before activation to the LD₁₀₀ after activation of the fraction with trypsin. Recently two papers have appeared describing the purification of ɛ-antigen. Verwoerd³ obtained crystalline prototoxin by methanol fractionation, but in yields too small for further investigation. Activation ratios were not given, so that the proportion of prototoxin to toxin could not be estimated. Orlans, Richards and Jones⁴ purified ɛ-toxin by a method similar to that reported here, but their best fraction contained considerable amounts of prototoxin and/or toxoid. As a part of work on these antigens, an attempt was made to purify prototoxin and, if possible, to obtain it free from ɛ-toxin. By a procedure which was simple and apparently without deleterious effect on the antigen, prototoxin was obtained in a crystalline form.