Hydroxymethylhydroperoxide as Inhibitor and Peroxide Substrate of Horseradish Peroxidase

Bis(hydroxymethyl)peroxide, formerly reported to inhibit horseradish peroxidase, was found not to influence the enzyme. Hydroxymethylhydroperoxide, which may be formed from bis(hydroxymethyl)peroxide by hydrolysis, irreversibly inhibits horseradish peroxidase in a second‐order reaction, k = 3.0X10 2 /sec −1 XM −1 at pH 4.27 in 6.7 mM guaiacol. Hydroxymethylhydroperoxide is a peroxide substrate of horseradish peroxidase. The rate constant ( k 1 ) for the formation of the enzyme‐substrate complex (Cpd I) between hydroxymethylhydroperoxide and horseradish peroxidase was indirectly determined to be 2X10 5 sec −1 XM −1 at pH 4.27.