Properties of catalase. Catalysis of coupled oxidation of alcohols

Abstract

It was previously shown (Keilin & Hartree, 1936) that on addition of ethanol and catalase to a primary oxidation system, such as xanthine oxidase and hypoxanthine, the rate of oxygen uptake is markedly increased and the final uptake is doubled.Similar results were obtained using other oxidizing enzymes, e.g.uricase and d-amino-acid oxidase and their respective substrates, in other words systems which react directly with molecular 02 and reduce it to H202.The increased 02 uptake was shown to be due to the secondary oxidation of ethanol to acetaldehyde by H202 formed in the primary oxidation reaction.It was a matter for some surprise to find that this secondary oxidation of ethanol took place only in presence of catalase, which catalyzes this reaction instead of preventing it by the usual catalatic decomposition of H202 into 02 and water.Since H202 formed in the primary oxidation reaction could be replaced by barium or cerium peroxide, but not by a solution of free H202, it appeared that the H202 oxidizing ethanol was in a 'nascent state'.In this paper we propose to deal with three aspects of this reaction: (1) the catalysis of the reaction by pure catalase in order to eliminate the possible presence of other catalytic systems reacting with alcohols, (2) the comparison of the rate of oxidation of different alcohols, and (3) the nature of the peroxide required for this oxidation reaction.This study will be concluded by a critical examination of the possible function of catalase.