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 pentaammine 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 mumol substrate oxidized min-1 mumol-1 enzyme. The effects of pH, temperature, and substrate concentration on the oxidation reaction were examined. The optimal temperature was determined to be 45 degrees C, and the optimal pH was 4.3. The Km and Vmax for veratryl alcohol were determined to be 3.519 mM and 52.27 microM min-1, respectively. Tartrate at concentrations as low as 0.10 mM was found to inhibit the reaction.