Ethanol, catalase action

Critically analyzing the mechanism (6.8)-(6.12), one may note the unsuitability of the currently presented interaction between complexes E-Fe3+—OH and E-Fe3+ OOH and substrates (H202 and H2D), because it is unclear how the substrate is activated. Moreover, intensification of the catalase reaction induces a non-classical peroxidase activity increase in ethanol and formic acid oxidation reactions. This indicates the existence of a unit common to these two processes [82, 83], The alternative action of catalase (catalase of peroxidase reaction) in the biosystem with solidarity of elementary stage mechanisms should be noted [88, 89], Peroxidase action of catalase requires a continuous supply of H202 for ethanol and formic acid oxidation, which can be explained by oxidation according to conjugated mechanism [90],... 

Ingested alcohol is metabolized to acetaldehyde mainly by the action of liver alcohol dehydrogenase. Catalase (21,22), the microsomal ethanol oxidizing system (MEOS) (23-25), and extrahepatic pathways have also been considered as ethanol metabolizers, but these systems probably play only a minor role in most cases (for a detailed discussion of ethanol metabolism, see review by Hawkins and Kalant, 26). Ethanol metabolism produce an increase in the NADH/NAD+ ratio in the liver... 

Meahlyi has recently studied the separation of the heme from the peroxidase and has observed several steps in the reaction. One of the steps varies as the square of the H+ concentration, which suggests that propionic acid links of the heme to the protein are ruptured in this reaction. It is interesting to note that it has not been possible to reversibly dissociate catalase, perhaps because the heme is too well buried below the protein surface to diffuse out. The peroxidase action of catalase.H202 is less for higher alcohols than for methanol and ethanol, also suggesting steric-hindrance owing to the size of the substrate molecule that can readily approach the iron atom. 

A new role for catalase, other than the decomposition of hydrogen peroxide, was discovered by Keilin and Hartree, who observed that in the presence of high concentrations of catalase and a suitable substrate, such as ethanol, hydrogen peroxide formed by enzymatic action was not decomposed but instead was used for the coupled oxidation of the substrate ... 

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