番茄芝麻斑病原菌产生的细胞壁降解酶种类及其活性变化

The kinds and activity of cell wall degrading enzymes produced from tomato Helminthosporium carposaprum pathogens

番茄芝麻斑点病原菌能够产生一系列细胞壁降解酶,即果胶甲基酯酶(PE)、多聚半乳糖醛酸酶(PG)、果胶甲基半乳糖醛酸酶(PMG)、多聚半乳糖醛酸反式消除酶(PGTE)、果胶甲基反式消除酶(PMTE)和纤维素酶(Cx)。酶动力学研究表明:产生的各种细胞壁降解酶均有特定的最适反应条件。水解酶类的PG、PMG、Cx最大酶活的pH均为5.0,温度均为50℃;裂解酶类的PGTE和PMTE最大酶活的pH均为9.0,温度均为30℃,与其他病菌产生的细胞壁降解酶的特性基本相同。在活体外,随着培养天数的增加PG、PMG、PGTE、PMGE、Cx的活性都大幅度增加,但所有酶活性都明显低于活体内的酶活性。

A series of cell wall degrading enzymes （CWDEs） including pectin methylesterase （PE）, polygalacturo- nase （PG）, polymethylgalacturonase （PMG）, polygalacturonic acid transeliminase （PGTE）, pectin methyl transeliminase （PMTE） and Cx were found in tomato Helrninthosporium cart）osaprum pathogens. The results from enzyme dynamics analysis showed that different kinds of CWDEs had special optimum temperatures, pH and reaction time for their maximum activities. For example, PG, PMG and Cx as a hydrolytic enzymes showed maxi- mum activities at pH 5.0 and 50 ℃ PGTE and PMTE as a lytic enzymes at 9.0 and 30 ℃. The activity of PG, PMG, PGTE, PMGE and Cx increased greatly with the day in vitro, but in vivo CWDEs showed higher activities as compared with those in vitro.