与番茄花柄脱落相关的多聚半乳糖醛酸酶的分离纯化和特性

Separation,Purification and Characterization of Polygalacturonase of Tomato Pedicel Related to Abscission

为弄清番茄花柄脱落相关酶——多聚半乳糖醛酸酶(polygalacturonase,PG)的性质,采用离体培养条件下经乙烯处理的番茄花柄,分离和纯化了多聚半乳糖醛酸酶并测定其性质。结果表明:用Sephadex G-75凝胶过滤层析和CM Sepharose CL-6B阳离子交换层析方法可分离纯化得到分子量约为30.2 kDa的多聚半乳糖醛酸酶,纯化倍数为30.85;纯化的PG活性最适pH值为5.0,最适反应温度为40℃;K_m值为26.14 mg·mL^(-1);1mmol·L^(-1)Ca^(2+)、Cu^(2+)、Ba^(26)、Co^(2+)和Mn^(2+)可抑制PG活性,而1 mmol·L^(-1)的Mg^(2+)、K^+、Fe^(2+)、Zn^(2+)、Fe^(3+)促进PG活性,20 mmol·L^(-1)的Fe^(2+)和Fe^(3+)促进效果尤为显著。

In order to clarify the characterization of the polygalacturonase （PG） related to abscission in tomato pedicel absciss.ion zone, a polygalacturonase was separated and purified from the ethylene-treated tomato pedicels cultured in vitro and characterized. The results indicated that the molecular mass of the purified polygalacturonase was 30.2kDa and the extent of purification was 30.85-fold by Sephadex G-75 chromatography gel and CM Sepharose CL-6B ion exchange chromatography. The pH optimum for activity was determined to be 5.0, temperature optima to be 40 ℃ and Km was 26.14 mg·mL^-1. The enzyme activity was inhibited by 1 mmol·L^-1 Ca^2＋, Gu^2＋, Ba^2＋, Co^2＋ and Mn^2＋, and was activated by 1 mmol·L^-1 Mg^2＋, K^＋, Fe^2＋, Zn^2＋ and Fe^3＋, especially by 20 mmol·L^-1Fe^2＋ and Fe^3＋.