Some immunochemical properties of penicillenic acid. An antigenic determinant derived from penicillin.

Under mild conditions, benzylpenicillin in aqueous solution rearranges to benzylpenicillenic acid, which reacts, under suitable conditions, to form stable disulfides and mercaptides. Through reaction with native proteins or especially with proteins that are enriched in SH groups ("thiolated"), penicillenic acid forms, ma mixed disulfide linkages, stable highly substituted conjugates. These conjugates are potent antigens, inducing the formation of substantial amounts of antibodies specific for the penicillenic acid structure. The implications of these findings for penicillin hypersensitivity in man are discussed.