| 摘 要： | Purified β-glucosidase fromCellulomonas biazotea had an apparentK
m andV for 2-nitrophenyl β-d-glucopyranoside (oNPG) of 0.416 mmol/L and 0.22 U/mg protein, respectively. The activation energy for the hydrolysis of pNPG
of β-glucosidase was 65 kJ/mol. The inhibition by Mn2+
vs. oNPG of parental β-glucosidase was of mixed type with apparent inhibition constants of 0.19 and 0.60 μmol/L for the enzyme
and enzyme-substrate complex, respectively. Ethanol at lower concentrations activated while at higher concentrations it inhibited
the enzyme. The determination of apparent pK
a’s at different temperatures and in the presence of 30 % dioxane indicated two carboxyl groups which control theV value. The thermal stability of β-glucosidase decreased in the presence of 10 % ethanol. The half-life of β-glucosidase in
1.75 mol/L urea at 35 °C was 145 min, as determined by 0–9 mol/L transverse urea gradient-PAGE.
This work was financed in part by a grant made by theUS Agency for International Development under PSTC proposal 6-163,USAID grant no. 9365542-G-00-89-42-00, and PAEC.
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