甲烷单加氧酶的催化性能

THE CATALYTIC PERFORMANCE OF METHANE MONOOXYGENASE FROM Methylomonas sp. GYJ3

研究了来源于Ｍｅｔｈｙｌｏｍｏｎａｓｓｐ．ＧＹＪ３菌的甲烷单加氧酶（ＭＭＯ）的催化性能．结果表明，当组成该酶的三个组分，羟基化酶、调节蛋白Ｂ和还原酶的摩尔比为１∶１．７∶２．０时，重组的ＭＭＯ体系酶的比活最高，为３４２ｎｍｏｌ／（ｍｇ·ｍｉｎ）．当反应体系的ｐＨ在６．５～７．５时，ＭＭＯ酶的活力最大．研究了纯ＭＭＯ催化甲烷羟基化反应和丙烯环氧化反应的特性，以及金属离子和电子给体对ＭＭＯ催化反应的影响．

The catalytic performance of methane monooxygenase (MMO) from Methylomonas sp. GYJ3 was studied. The results showed that the efficient propene epoxidation coupling with NADH oxidation requires all three components of the MMO. The MMO activity of the reconstituted system reached 342 nmol/(mg·min) when the molar ratio of hydroxylase, regulatory protein B and reductase was 1∶1 7∶2 0. The optimum pH range was 6 5 to 7 5. The hydroxylation of methane and epoxidation of propene catalyzed by purified MMO were investigated. In addition, some metal ions can stimulate the MMO activity, implying that the MMO activity was closely related to metal ions. A variety of reducing agents were selected as electron donor but only NADPH could replace NADH.