Continuous photometric determination of endo-1,4-beta-D-glucanase (cellulase) activity using 4-methylumbelliferyl-beta-D-cellobioside as a substrate.

A very simple and sensitive procedure for the determination of the activity of highly purified endo-1,4-beta-glucanase from the microscopic fungus Trichoderma reesei using 4-methylumbelliferyl-beta-D-cellobioside has been developed. The HPLC study has shown that this substrate is cleaved by endo-1,4-beta-glucanase to form predominantly free 4-methylumbelliferone, Km and kcat being 1.25 mM and 7.9 s-1, respectively (30 degrees C, pH 5.0). The possibility of continuous photometric determination of the enzyme using the difference absorptivity coefficient of 1600 M-1 cm-1 at 350 nm has been demonstrated.