Attachments of pentaammineruthenium(III) to Trichoderma reesei cellobiohydrolase I increases its catalytic activity

Pentaammineurthenium(III) was covalently attached to cellobiohydrolase I (CBH I, EC 3.2.1.91), the major component of Trichoderma reesei cellulase, resulting in 0.7 mol ruthenium/mol CBH I and an electrode potential of +95 mV. Fractionation of modified CBH I by chromatofocusing resulted in the separation of fractions with a 1.4- to 3.2-fold increase in specific activity toward p-nitrophenylcellobioside, depending on the assay conditions, over that of native enzyme. The extent of the hydrolysis of insoluble cellulosic substrates (Avicel and newsprint) to glucose by modified CBH I was also greater than that observed by the native enzyme.