Influence of temperature on kinetic parameters for hydrolysis of insoluble cellulose by Cellobiohydrolase Cel7A

The enzymatic hydrolysis of the resistant lignocellulose to fermentable sugars is a challenging step in the production of second generation bioethanol. Cellobiohydrolase Cel7A catalyzes the hydrolysis of cellulose from the reducing end in a processive manner. The reaction rate of the hydrolysis of insoluble cellulose by cellobiohydrolase Cel7A can be described on the basis of steady state theory for processive cellulases. According to this theory the processive reaction rate can be expressed as a hyperbolic function which is related to the Michaelis-Menten equation. By applying the processive steady-state theory we have studied the influence of temperature on kinetic parameters (Km and Vmax) of Cel7A catalyzed hydrolysis. Vmax and Km have been determined over a temperature range from 25° C – 60 °C. The process of making bioethanol from lignocellulose often comprises enzymatic action at elevated temperatures. Thus, knowledge of kinetic parameters at elevated temperatures is important since it offers a preview on the mechanism of cellulases at applied conditions.