Homogeneity and molecular weight of toxin of Clostridium botulinum type B

Gerwing et al. described the isolation and purification from culture filtrates of the toxin of Clostridium botulinum type B and characterized it as a homogeneous protein of less than 10,000 molecular weight. Analysis by various methods of samples of this toxin obtained from Gerwing et al., and preparations produced by their methods in our laboratories, furnished convincing evidence that neither her preparation nor ours was homogeneous. The molecular weight of the toxic component isolated from either of the preparations was 100,000 or greater and resembled, in a number of respects, the alpha component isolated by us from the crystalline toxin of C. botulinum type A.