Veratryl alcohol oxidase activity of a chemically modified cellulase protein

A cellulase, cellobiohydrolase I (CBH I) from Trichoderma reesei was chemically modified by covalent attachment of pentaamine ruthenium (III) without loss in hydrolytic activity. Data suggest that such a modification endowed CBH I with oxidoreductase activity. The modified enzyme was able to carry out hydrogen peroxide-dependent oxidation of veratryl alcohol, a substrate for lignin peroxidase, at a rate of 0.148 μmol substrate oxidized min^-1 μmol^-1 enzyme. The effects of pH, temperature, and substrate concentration on the oxidation reaction were examined. The optimal temperature was determined to be 45°C, and the optimal pH was 4.3. The K(m) and V(max) for veratryl alcohol were determined to be 3.519 mM and 52.27 μM min^-1, respectively. Tartrate at concentrations as low as 0.10 mM was found to inhibit the reaction.