大豆过氧化氢酶的分离纯化及性质研究

新鲜大豆芽经匀浆、磷酸缓冲液抽提、硫酸铵分级沉淀、DEAE-Sepharose离子交换层析、Superdex-200凝胶过滤层析，获得电泳纯的过氧化氢酶。该酶酶活回收率为30.92%，纯化倍数为293.09，酶比活力达到26 322.43 U/mg。该酶全分子质量为234.9 kD，亚基分子质量为57.42 kD；最适pH值为7.2，最适温度为30 ℃，在pH 4.0～10.6及25～35 ℃范围内有较好的稳定性；在30 ℃、pH 7.2条件下测得该酶对过氧化氢的Km值为31.82 mmol/L；十二烷基硫酸钠、草酸、Ag+、Cu2+对该酶有强烈的抑制作用，Pb2+对该酶有双重作用，低浓度时有激活作用而高浓度时抑制酶活性。

Isolation,Purification and Partial Characterization of Catalase from Soybean (Glycine max)

Electrophoresis-purity catalase (CAT) was obtained from freshly sprouted soybean (Glycine max) by the
sequential steps of homogenization, buffer solution extraction, ammonium sulfate precipitation, DEAE-Sepharose ion
exchange chromatography and Superdex-200 gel filtration chromatography. The purified enzyme had a specific activity of
26 322.43 U/mg, with a 30.92% activity recovery and a 293.09-fold purification. The molecular mass of the CAT enzyme
comprising a 57.42 kD subunit was 234.9 kD. Its optimum pH and temperature were 7.2 and 30 ℃, respectively. This
enzyme was stable at pH 4.0–10.6 and at 25–35 ℃. Its Km towards H2O2 was 31.82 mmol/L. The enzyme activity was
strongly inhibited by sodium dodecyl sulfate (SDS), oxalic, Ag+ and Cu2+, but was activated by low concentration of Pb2+.