β-D-半乳糖苷酶

分子量: 540,000 最适pH: 7.0~7.5 最适温度: 50~55℃ 等电点: 4.6 测定方法: 1. 原理 2.试剂 A. 0.1 mol/L 磷酸盐缓冲液, pH 7.3 B. 3.36 mol/L 巯基乙醇溶液 C. 30 mmol/L MgCl2溶液 D. 34 mmol/ ONPG溶液 E. 50 mmol/L磷酸盐缓冲液，含1 mmolL MgCl2, pH 7.3 F. 酶溶液 [取本品8 mg，加入试剂E制成100 mL混合液。再取该混合液1 mL，加入试剂E制备酶溶液(0.8 μg/mL溶液)。 ] 3. 步骤 于37℃条件下测定410nm波长处吸光度变化2~3分钟，记录各反应孔数据。 将反应初始直线段一分钟内的吸光度变化值定义为ΔA。 4.单位定义 在上述反应条件下，每分钟催化生成1微摩尔邻硝基苯酚的酶量定义为1个活性单位。 计算 3.5: o-硝基苯酚 （ONP）毫摩尔吸光系数 3.1: 溶液总体积 (mL) S: 本品取用量 (mg) Molecular weight: 540,000 Optimal pH: 7.0~7.5 Optimal temperature: 50~55℃ Isoelectric point: 4.6 Assay method: 1. Principle 2. Reagents A. 0.1 mol/L phosphate buffer, pH 7.3 B. 3.36 mol/L mercaptoethanol solution C. 30 mmol/L MgCl2 solution D. 34 mmol/ ONPG solution E. 50 mmol/L, phosphate buffer containing 1 mmolL MgCl2, pH 7.3 F. Enzyme solution [Add Reagent E to 8 mg of this product to obtain 100 mL of mixture. Add Reagent E to 1 mL of the mixture to prepare 100 mL of enzyme solution (0.8 μg/mL solution).] 3. Procedure The change in the absorbance in each cell at a wavelength of 410nm at 37℃ for 2~3 minutes is recorded. The change in the absorbance from the initial straight line for one minute is specified as ΔA. 4. Unit definition The amount of enzyme producing 1 μmol of o-nitrophenol within one minute under the above-mentioned reaction conditions is specified as 1 unit. Calculation 3.5: millimolar absorptivity of ONP 3.1: total volume of solution (mL) S: measured volume of this product (mg)

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