Studies on Peroxidative Detoxification of Purified Diphtheria Toxin

The mechanism of the peroxidative oxidation of diphtheria toxin has been investigated. It has been found that this reaction requires the presence of an oxidizable, dialyzable cofactor in addition to hydrogen peroxide and peroxidase. Cofactors are present in a variety of materials and have been partially purified from urine. The flocculation titer of toxin modified by peroxidation remains unchanged even after 99 per cent or more of the toxicity has been destroyed. The change thus appears analogous to the conversion of toxin to toxoid in the presence of formalin. It is suggested that the well known conversion of crude diphtheria toxin to toxoid which occurs on storage or aging may be due to a slow peroxidative process.