蜗牛酶中一种β-葡萄糖苷酶的纯化及酶学性质的研究

通过DEAE-Sepharose离子交换层析和Sephadex G-100凝胶过滤层析的联用从中华白玉蜗牛消化酶中分离出1种具有人参皂苷Rb_1水解活性的β-葡萄糖苷酶.纯化后该酶在SDS-PAGE上呈单一蛋白质条带.反应最适pH为5.6,最适温度是80 ℃.pH稳定范围很广,在pH为4.0～11.0的溶液中和温度60 ℃以下保持长时间稳定状态,是一个耐碱和中等耐热的糖苷酶.Na~+、K~+、Li~+、Ca~(2+)、Mg~(2+)、EDTA、DTT和SDS不影响该酶活性,而Cu~(2+)、Ag~+和Fe~(3+)对该酶则具有明显的抑制作用.pNPG为底物的动力学参数Km和Vmax分别为0.182 mmol/L和0.189 μmol/(min·mg).

Purification and enzyme properties of a β-glucosidase from helix snailase

The β-glucosidase which could hydrolyze the ginsenoside-Rb_1 was purified from Helix snailase through a combination of DEAE chromatography and gel filtration chromatography. The β-glucosidase was purified to apparent homogeneity on SDS-PAGE. The optimum pH was 5.6 and the optimum temperature was 80 ℃. The enzyme was stable below 60 ℃ and from pH 4 to 11. The presence of Na~+ ,K~+ ,Li~+,Ca~(2+),Mg~(2+),EDTA,DTT and SDS had no obvious effect on the enzyme activity,while Cu~(2+) ,Ag~+ and Fe~(3+) ions play an inhibitory role. The Km and Vmax values for β-D-glucopyranoside (pNPG) as the substrate were calculated to be 0.182 mmol/L and 0.189 units/mg of protein respectively.