[关键词]
[摘要]
探讨来源于康氏木霉诱变菌株SG0026 10L发酵罐发酵液中纤维素酶系的分离纯化过程及其酶学性质。采用硫酸铵盐析、Sephadex G-100凝胶过滤、DEAE-Sepharose FF阴离子交换层析柱和CM-Sepharose FF阳离子交换层析等分离纯化技术,从康氏木霉诱变菌株发酵液中分离纯化得到3个电泳纯的纤维素酶系组分(内切葡聚糖酶、外切葡聚糖酶和β-葡萄糖苷酶)。对纯化的电泳纯内切葡聚糖酶、外切葡聚糖酶和β-葡萄糖苷酶的酶活进行测定,发现3种酶的比活力分别为4.67±0.06 IU/mg、5.16±0.08 IU/mg和12.52±0.12 IU/mg。采用变性聚丙烯酰胺凝胶电泳(SDS-PAGE)确定其分子量,发现其分子量分别为78.1、91.2和83.1kDa。利用Linewaeaver-Burk法对3种酶的动力学参数进行测定,发现3种酶的Km值分别为3.84、6.62和6.21 mg/mL,Vmax值分别为2.29、1.74和2.19 mg/(min?mL)。在此基础上,对3种酶的反应温度和pH进行了研究,发现3种酶的最适反应温度分别为50、50和55 ℃,最适反应pH均为5.0。
[Key word]
[Abstract]
Cellulase purification from the broth of the mutant strain Trichoderma koningii SG0026 allowed for the investigation of the enzymatic properties of its cellulase system. Three electrophoretically pure components of the cellulase system (endo-β-1,4-glucanase, exo-β-1,4-glucanase, and β-glucosidase) were isolated and purified from the broth of the mutant strain Trichoderma koningii SG0026 by a combination of ammonium sulfate fractionation, Sephadex G-100 gel filtration, DEAE-Sepharose FF anion exchange column chromatography, and CM-Sepharose FF cation exchange chromatography. The specific enzyme activities of electrophoretically pure endo-β-1,4-glucanase, exo-β-1,4-glucanase, and β-glucosidase were measured to be 4.67 ± 0.06, 5.16 ± 0.08, and 12.52 ± 0.12 IU/mg, respectively. The relative molecular masses of three cellulases were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and were 78.1, 91.2, and 83.1 kDa, respectively. The Lineweaver-Burk method was used to calculate the kinetic parameters of the three cellulases; the Km values for endo-β-1,4-glucanase, exo-β-1,4-glucanase, and β-glucosidase were 3.84, 6.62, and 6.21 mg/mL, respectively and the Vmax values were 2.29, 1.74, and 2.19 mg/(min?mL), respectively. Based on the results, the reaction temperature and pH of these three cellulases were determined. The optimal temperatures for endo-β-1,4-glucanase, exo-β-1,4-glucanase, and β-glucosidase were 50, 50, and 55℃, respectively, and their optimum pH values were 5.0.
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[基金项目]
国家自然科学基金项目(30270135);安徽省高等学校省级自然科学研究重点项目(KJ2013A049)