The Biochemical Properties And The Catalytic Properties Ofβ-glucosidase Bgl

With the development of the cellulosic as renewable resources, the applied value of β-glucosidase has taken domestic and foreign researchers’attention. β-glucosidase belongs to one of the cellulase systems, which is widely distributed in nature, and existing in plants, animals and microorganisms. β-glucosidase can catalyzes the hydrolysis of glycosidic bond between aryl or alkyl-and sugar-based radicals, which generate glucose. At present, the application of the β-glucosidase has been widely extended to the enzymatic extraction of the active substance of Chinese herbal medicine, in order to lower the cost of production and to make the extraction of drugs safer. A lot of research results show that the physiological activity of soy isoflavones comes from the activity of the isoflavone aglycones. What’s more it is easily for human beings to absorb aglycone isoflavones. β-glucosidase is used in the hydrolysis of soy isoflavone glycoside substances to make the preparation of soy isoflavone-rich soy isoflavone aglycones health food. Therefore, the use of bio-enzymatic extraction of soy isoflavones to biologically active aglycone substances is of great significance. In recent years, a large number of in-depth studies at home and abroad have been made about the safety of β-glucosidase hydrolyzed soy isoflavone glucoside. This project seeks to grasp the biochemical characteristics and catalytic properties of β-glucosidase, and to get a higher value in the industrial application.This project takes the β-glucosidase bgl, which is isolated by our laboratory, as our own research object. The molecular mass is77Kda as estimated by SDS-PAGE. The results show that:optimal conditions for activity are pH3.5and a temperature of90℃. Besides, β-glucosidase has the stronger heat stability, which can keep the activity of2h when at85～90℃and have a half life at95℃for50min. Co2+, DMSO, methanol and ethanol enhanced its activity, while Hg2+causes obvious inhibition. The substrate specificity of β-glucosidase bgl is pNPG. After comparison of the kinetic parameters of β-glucosidase, it was found that the pNPG, had Km and Kcat/Km, which was1.34±0.09mmoL/L and47.67±1.72mmoL/L-1*s-1respectively; the cellobiose had Km and Kcat/Km,which was0.52±0.04mmoL/L and1.97±0.02mmoL/L-1*s-1;the salicin had Km and Kcat/Km,which was3.21±0.48mmoL/L and4.73±0.4mmoL/L-1*s-1. Take cellobiose as the substrate, there is no effect on β-glucosidase bgl between5-30%concentration of DMSO, compared to the non-added activity of the DMSO; β-glucosidase bgl activity is limited between5～30%concentration of [EMIm]Ac and the hydrolysis of cellobiose gradually weakened with increasing concentration. The experimental results show that β-glucosidase bgl have better enzymatic properties and a great industrial value.In addition, this paper utilizes to research the application of β-glucosidase bgl in hydrolyzed soy isoflavone glucoside, and it describes high performance liquid chromatography. The results show that:the optimal reaction conditions of the enzymic hydrolysis of soybean composite function factor were as follows:pH3.5, temperature90℃, time1h, adding enzyme80.68U. Under the optimal condition,the glycoside hydrolysis by enzyme reached were96%. The experiment results indicate that the effect of enzymic hydrolysis soybean isofavone is obvious. The optimal reaction conditions of the enzymic hydrolysis of alcohol extract of soy isoflavones were as follows:pH3.5, temperature90℃, time1h, adding enzyme80.68U. Under the optimal condition,the glycoside hydrolysis by enzyme reached were68%. The experiment results indicate that the effect of enzymic hydrolysis soybean isofavone is evident.