title: [Preparation of baicalein using thermophilic and sugar-tolerant beta-glucosidase].
abstract: The reaction conditions of baicalin hydrolyzed into baicalein by a kind of thermophilic and sugar-tolerant beta-glucosidase were studied in this paper. The beta-glucosidase could catalyze baicalin into baicalein well in the acetic acid-sodium acetate buffer. The optimal enzyme activity was at 85 degrees C and pH 5.5. The enzyme was stable at the temperature less than 85 degrees C and pH range of 5-7.5. The maximum reaction rate V. and michaelis constant K. were 0.41 mmol x L(-1) x min(-1) and 3.31 mmol x L(-1) respectively. Different metal ions had different effects on the activity of enzyme. Na+ existing in acetic acid-sodium acetate buffer had an activation effect on enzyme. The enzyme activity was enhanced by the concentrations of glucose below 0.6 mol x L(-1), and was gradually inhibited when monosaccharide concentration was over 0.6 mol x L(-1). When the monosaccharide concentration reached 1.2 mol x L(-1), the inhibition rate of enzyme activity was about 50%, which showed good glucose tolerance. The good reaction conditions through the experiment have been determined as follows, the substrate: enzyme dose was 1 g: 0.2 mL, acetic acid-sodium acetate buffer pH 5.5, reaction temperature 85 degrees C, reaction time 10 h, and the enzymatic hydrolyzation ratio could reach 97%.
authors.forename: Shi-ping
authors.initials: SP
authors.lastname: Li
authors.forename: Jian-hui
authors.initials: JH
authors.lastname: Wen
authors.forename: Yi-wu
authors.initials: YW
authors.lastname: Zhao
authors.forename: Wen-zhe
authors.initials: WZ
authors.lastname: Huang
authors.forename: Jian-jun
authors.initials: JJ
authors.lastname: Pei
authors.forename: Zhen-zhong
authors.initials: ZZ
authors.lastname: Wang
authors.forename: Lin-guo
authors.initials: LG
authors.lastname: Zhao
authors.forename: Wei
authors.initials: W
authors.lastname: Xiao
mesh_terms: D055162:Biocatalysis; D004795:Enzyme Stability; D044950:Flavanones / Q000737:chemistry*; D005419:Flavonoids / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D006358:Hot Temperature; D006868:Hydrolysis; D007700:Kinetics; D001617:beta-Glucosidase / Q000737:chemistry*
chemical_list: D044950:Flavanones; D005419:Flavonoids; C038044:baicalin; C006680:baicalein; D001617:beta-Glucosidase; D005947:Glucose