Enzymatic analyses in organic solvents.

Horseradish peroxidase has been found to vigorously act as a catalyst in a number of water-immiscible organic solvents. The rates of peroxidase-catalyzed oxidation of p-anisidine with H(2)O(2) in toluene, benzene, ethyl and butyl acetates, and ether are in the range of 10-25% of that in water (pH 7.0) at the same reactant concentrations. Per oxidase was coupled with cholesterol oxidase (which was also found to be catalytically active in organic media), and the bienzymic system was successfully used for accurate, reliable, and reproducible determination of cholesterol in toluene.