مشخصات پژوهش

Cellulases belonging to glycoside hydrolases (GH) superfamily catalyze hydrolysis cellulose polymer containing β- 14-glycosidic bond. These enzymes are Multimodular ezymes which have a great number of applications in various industrial sections, especially in the production of biofuel from widespread and renewable biomass, that is, cellulose. The accessory domains of Cellulase influence characteristics of the catalytic domain; consequently, determining the function of accessory domains and the contribution of individual accessory domains to the enzyme activity would be beneficial to engineering of cellulose enzymes with high activity and stability. Ig-like domains are widely distributed in glycoside hydrolase superfamily, but their function is unclear in some enzymes such as AaCel9A. Endoglucanase Cel9A from Alicyclobacillus acidocaldarius (AaCel9A) is a monomer of 537 residues being composed of a C-terminal GH9 catalytic domain and an N-terminal Ig-like domain. Except for molecular dynamic simulation, no laboratory reports on the role of Ig-like domain of this enzyme have been proposed. In this study, at first, expression vector that includes the sequence encoding AaCel9A enzyme without Ig-like domain was transferred into expression host. After expression and purification of AaCel9A enzyme without the Ig-like domain, its biochemical properties like pH and temperature optima and Kinetic parameters were determined and compared with wild-type enzyme’s data. Our results shows that the deletion of the Ig-like domain has increased the catalytic efficiency of the enzyme up to three folds without any significant changes in Km of the enzyme. Moreover, pH and temperature of the optimal activity of the enzyme have been changed by the deletion of Ig-like domain.