Recyclable Thermoresponsive Polymer-beta-Glucosidase Conjugate with Intact Hydrolysis Activity

摘要

beta-Glucosidase (BG) catalyzes the hydrolysis of cellobiose to glucose and is a rate-limiting enzyme in the conversion of lignocellulosic biomass to sugars toward biofuels. Since the cost of enzyme is a major contributor to biofuel economics, we report the bioconjugation of a temperature-responsive polymer with the highly active thermophilic beta-glucosidase (B8CYA8) from Halothermothrix orenii toward improving enzyme recyclability. The bioconjugate, with a lower critical solution temperature (LCST) of 33 degrees C withstands high temperatures up to 70 degrees C. Though the secondary structure of the enzyme in the conjugate is slightly distorted with a higher percentage of beta-sheet like structure, the stability and specific activity of B8CYA8 in the conjugate remains unaltered up to 30 degrees C and retains more than 70% specific activity of the unmodified enzyme at 70 degrees C. The conjugate can be reused for beta-glucosidic bond cleavage of cellobiose for at least four cycles without any significant loss in specific activity.