Résumé
In the current study, one thermostable endoglucanase was purified from Penicillium notatum NCIM NO-923 through mixed solid state fermentation of waste cabbage and bagasse. The molecular weight of the purified enzyme was 55kDa as determined by SDS polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme had low activation energy (Ea) of 36.39KJ mol-1 for carboxymethyl cellulose hydrolysis and the enthalpy and entropy for irreversible inactivation was 87 kJ mol −1 and 59.3 J mol −1 K−1 respectively. The enzyme was quite thermostable with a Tm value of 62.2˚C. The pKa1 and pKa2 of ionizable groups of the active sites were 2.5 and 5.3 respectively. Apparent Km, Vmax and Kcat of the enzyme were found to be 5.2 mg mL-1, 80 U/gds and 322.4 sec-1 respectively. The enzyme showed about 1.4 fold increased activity in presence of 10mM MgSO4. Adsorption of endoglucanase on Avicel at wide pH range was studied at different temperatures. Langmuir type adsorption isotherm at 10˚C showed maximum adsorption strength of enzyme at pH 3.0, which was in a range of optimum pH of the enzyme.