tBOOH Acts as a Suicide Substrate for Catalase

The effects of t-butyl hydroperoxide (tBOOH) on bovine liver catalase were investigated. tBOOH is accepted as a substrate of catalase and in the absence of hydrogen donors leads to a destruction of the enzyme via compound II formation. During the decomposition of this enzyme-substrate complex catalase serves as internal hydrogen donor which results in destruction of the enzyme. Evidence for this destruction is given by:-a decrease of the Soret band in the uv/vis spectrum,-iron release from the enzyme,-decrease of the catalatic activity of the enzyme measured by oxygen release from hydrogen peroxide.Hydrogen donors like NADH and o-dianisidine have been found to protect the enzyme from destruction by tBOOH but lead to a structural alteration of the enzyme, shown by alteration of the electrophoretic mobility. In the presence of the hydrogen donor tBOOH is completely reduced to t-butanol, which is thought to proceed in a peroxidaselike reaction.