Abstract

Sporocytophaga sp., a Gram-negative aerobic cellulose decomposing bacterium, is capable of gliding on the surface of solid medium. A new endoglucanase, carboxymethylcellulase (CMCase1), was purified from an aerobic bacteriumSporocytophaga sp. JL-01. The molecular weight of the enzyme was 82 kDa as determined by SDS Polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH was 5.0 and optimum temperature was 50°C under experiment conditions. The Km of CMCase1 was 9 mgml^-1 and Vmax was 27.3 ug min^-1mg^-1 protein. The Zn²⁺ could inhibit the activity of this enzyme at ion concentration of 5 mM. RP-HPLC revealed that aromatic amino acid, acidic amino acid, and basic amino acid accounted for 10.5, 24.5 and 7.0%, respectively. The far-UV circular dichroism (CD) spectrum showed that the amount of β-sheet was decreased with the temperature changed from 25 to 75°C.

Key words: Sporocytophaga, carboxymethylcellulase, enzyme characteristics, circular dichroism spectrum