Purification and characterization of two components of botulinum C2 toxin

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Abstract
Two dissimilar proteins, designated as components I and II, of botulinum C2 toxin elaborated by strain 92-13 were purified to a homogenous state. The MW determined by sodium dodecyl sulfate gel electrophoresis were 55,000 for component I and 105,000 for component II. Whereas each component showed no or feeble toxicity even after being treated with trypsin, the toxicity was elicited when these 2 components were mixed and trypsinized. The toxicity of the mixture of components I and II at a ratio of 1:2.5 on a protein basis was 2.2 .times. 104 mouse i.p. LD50/mg of protein and increased by 2000 times or more when treated with trypsin. The molecular characteristics of botulinum C2 toxin differ from those of the toxin of Clostridium botulinum types A through F in that C2 toxin is constructed with 2 separate protein components, which are not covalently held together and that its toxicity is elicited by cooperation of the 2 components.