茎用芥菜芥子苷酶的分离纯化及组成研究

Study on Isolation,Purification and Molecular Characteristics of Myrosinase from Brassica juncea Coss,var.tumida Tsen et Lee

以茎用芥菜为原料,采用磷酸缓冲液浸提、(NH4)2SO4盐析、DEAE-52和Sephadex G-100色谱对其中的芥子苷酶予以分离纯化,并就该酶的分子特性进行了研究。通过DEAE-52和Sephadex G-100色谱纯化后,回收具有芥子苷水解活性的蛋白质峰。该芥子苷酶的分子质量为105000(凝胶法);紫外最大吸收峰位于277.3nm;每摩尔酶分子有1.34mol自由巯基;组成酶的氨基酸中,Leu和Gly含量较高,Cys和Lys含量较低。

Isolation and purification and molecular characteristic of a myrosinase, which was isolated and purified from the extraction by ammonium sulfate, DEAE-52 and Sephadex G-100 chromatography were studied. The recovery and activity of myrosinase was determined during isolation and purification. By DEAE-52 and Sephadex G-100 chromatography, an active peak was recovered. Molecular weight of the enzyme was about 105000 as assayed by gel filtration of Sephadex G-100. This enzyme exhibited one absorption maximum in the ultraviolet range at 277.3 nm.The enzyme contained free thiol. The amino acid compositions analysis indicated that high Leu and Gly content and low Cys and Lys content.