Properties of two endoglucanases from a mutant strain Trichoderma sp. M7 with potential application in the paper industry.

Two endoglucanases were purified to electrophoretic homogeneity from the culture filtrate of a mutant strain Trichoderma sp. M7. EG-III and EG-IV had Mr of 49.7 and 47.5 kDa, and estimated pI values of 3.7 and 6.35, respectively. The optimal pH and temperature values were determined to be pH 5.0 and 60 degrees C for the first cellulase, whereas pH 5.2 and 50 degrees C were optimal for the other. Endoglucanases exhibited typical Michaelis-Menten kinetics with Km and V values of 2.9 mg ml(-1) and 60498.5 micromol min(-1) mg(-1) for EG-III and 3.8 mg ml(-1) and 22650.9 micromol min(-1) mg(-1) for EG-IV, respectively. Mn2+, Cu2+ and Pd2+ strongly inhibited the enzymes. EG-IV catalyzed the hydrolysis of Na-CMC and hydroxyethyl cellulose (HEC) only, whereas EG-III displayed high activity towards xylans, also. Different preferences towards cellulosic substrates and their regions define a different role of the investigated enzymes in the degradation of plant biomass.