Increased yield of β-glucosidase-catalyzed hydrolysis reactions in the presence of betaine-type metabolite analog

beta-Glucosidases (EC 3.2.1.21), abundant enzymes distributed in animals, plants and microorganism, has been generating lots of attentions for bioethanol production from cellulosic biomass. In this study, using three different origins of beta-glucosidases, glucose productivity of beta-glucosidase-catalyzed hydrolysis reactions in the presence of synthetic betaine-type metabolite analog (2-N,N,N-tri-n-butylammonium) acetate, was investigated. By the addition of the analog, the hydrolysis yields for all beta-glucosidases was highly improved from 4-13 to 64-100 %. To understand the factors affecting on the yield enhancements, the kinetic parameters, inhibition constants of end-product and temporal stability of beta-glucosidases were compared. As a result, enhancement of the yields is mainly related to the increase in the temporal stability of beta-glucosidases in the presence of the analog. The present findings lead to not only improve the glucose productivity of beta-glucosidase-catalyzed hydrolysis reaction toward bioethanol production but also apply to a new stabilization method for various unstable enzymes.