The biochemistry of bacterial toxins

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Abstract
II. The action of C. welchii toxin on a sample of crude sphingomyelin was examined. Approx. 90% of the lipin P was converted into a water-soluble form; the hydrolysis was slower than that of lecithin P in similar conditions, but like that of lecithin, was activated by Ca ions and inhibited by NaF. Phosphorylcholine was recovered quantitatively from the hydrolysis products, together with a P-free product approximating to the composition of lignocerylspingosine, which was not obtained pure. The maximum hydrolysis of lipin P in mixed lecithin-kephalin prepns. corresponded with the percentage content of non-amino (lecithin) N. It is concluded, from the manner of hydrolysis, that C. welchii lecithinase hydrolyzes sphingomyelin, as well as lecithin, with production of phosphorylcholine, but does not attack phosphatidylethanolamine nor phosphatidylserine.[long dash]III. C. oedematiens culture filtrates contain a lecithinase similar in biochemical properties to that present in C. welchii filtrates. The lecithinases present in C. oedematiens type A and type B filtrates are immunologically distinct from each other, and from C. welchii lecithinase, in that their activity is inhibited by a homologous but not inhibited by a heterologous antitoxic serum. The type A and type B lecithinase are probably identical respectively with the gamma- and beta-toxins of C. oedematiens filtrates. C. oedematiens type A toxins also contain a lipase, which is possibly identical with the factor (epsilon-toxin) responsible for the "pearly layer" effect in colonies of this organism. Culture filtrates of certain strains of C. sordellii also contain a lecithinase which is not yet characterized.

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