Purification and partial characterization of the exotoxin of Corynebacterium ovis.

1. The toxin from Corynebacterium ovis, a phospholipase D (sphingomyelin phosphodiesterase D) that acts on 2-lysophosphatidylcholine and sphingomyelins, was purified by about 400-fold to homogeneity as judged by several criteria. [The EC number of the toxin (EC 3.1.4.41) has been allotted by the Nomenclature Committee of IUB, but has not yet been published.] 2. A new assay method performed in vitro, based on inhibition by the toxin of erythrocyte lysis by staphylococcal beta-haemolysin, was developed to facilitate the purification. 3. The toxin was found to be a basic (pI9.1) glycoprotein of mol.wt. 14,500 +/- 1,000. 4. The amino acid composition of the toxin was highly reminiscent of that of collagen, since it contained hydroxyproline, hydroxylysine and a high proportion of glycine, but preliminary tests showed no other similarities to collagen or proteins with similar compositions.