Glycosyl rotation and distortion by key residues in Endocellulase Cel6A from Theromobifida fusca.

Endocellulases are one kind of the important biodegrading cellulose enzymes. Experimental results show that a rotated and distorted preactivated structure exists before the substrate entering the transition state. The molecular dynamic simulation of endocellulase Cel6A models revealed a correlation between the rotation and distortion of pyranoside ring in -1 glycosyl unit of the substrate. The two key residues, Tyr73 and Ser189, in Cal6A cooperate to rotate and distort the pyranoside ring in the cellulose hydrolysis.