Kinetics of the reaction of hydrogen peroxide with cysteine and cysteamine

The rate of the reaction between hydrogen peroxide and cysteine or cysteamine is proportional to [H2O2] and [NH3+CHXCH2S–](X = H or CO2–) consistent with nucleophilic attack by the thiolate ions on peroxide oxygen. The rate decreases at higher pH where loss of the NH3+ proton occurs, and it is suggested that hydrogen bonding between this group and hydrogen peroxide facilitates the reaction.