Abstract
Papain, after its incubation with thiamine propyldisulfide (TPD) at pH 7.4,37℃ for 1 hour, was repeatedly precipitated by satulated NaCl solution and the precipitated papain was proved to be inactive, unless cysteine was added. TPD-inactivated papain was shown to be S-propylmercapto-papain by means of paper chromatography. S-Propylmercapto-papain was also isolated from TPD-inhibited papain by fractionated filtration through Sephadex G-25 column. S-Propylmercapto-papain was shown to be more resistant to the reaction with ICH_2-COOH or H_2O_2 but less resistant to heat-inactivation than papain.
