Reactivity toward cysteine of antimicrobial carbamimidothioic acid phenylalkylesters salts

The rates of reaction toward cysteine of a series of carbamimidothioic acid phenylmethylesters halides were investigated in phosphate buffer pH 7.4 at 37 degrees C under pseudo-first-order conditions. The reaction involves nucleophilic attack of cysteine on the C-S bond of isothiouronium mojety and corresponding benzenemethanethiols were detected as product of the reaction. Apparent first-order rate constants were determined.