Purification and characterization of bacterial CM-cellulase from camel rumen fluid [Camelus dromedarius]

ABSTRACT

Bacterial CM-cellulase [1,4-beta-D-glucanohydrolase, [EC 3.2.1.4]] from camelrumen fluid, an enzyme that causes a random secession of cellulose chainyielding glucose and cellotriose, was purified and characterized. Thepurification procedure included ammonium sulfate precipitation andchromatographies on DEAE-cellulose, and Sepharose 6B columns. By ion exchangeon DEAE-cellulose, five isoenzymes of CM-cellulase were obtained. CM-cellulase CII, CIV and CV were purified 11.2, 13.9 and 25.9 fold with 17.3%, 12.5% and 13.7% recovery in activities, respectively. The molecularweights of CM-cellulase CII, CIV and CV were estimated to be 12000, 13000 and 14600, respectively, for the native and 13000 for the denatured enzymes,respectively, suggesting that isoforms are monomeric. Amino acid compositionof the three CM-cellulases were detected. CM-cellulases CII, CIV and CV hadisoelectric points at 5.1, 6.6 and 5.1 and km values of 8.3, 6.25 and 5 mgCM-cellulase/ml, respectively, with more affinity toward CM-cellulase. CM-cellulases CII and CV had similar temperature optima at 40C, while themaximum activity for cellulase CIV was at 50C and had identical pH optimaat 5.5. The effect of divalent metal cations and different inhibitor on thethree isoenzyme activities was examined