A monohalomethane-producing enzyme, S-adenosyl-L-methionine-dependent halide ion methyltransferase (EC 2.1.1.-) was purified from the marine microalga Pavlova pinguis by two anion exchange, hydroxyapatite and gel filtration chromatographies. The methyltransferase was a monomeric molecule having a molecular weight of 29,000. The enzyme had an isoelectric point at 5.3, and was optimally active at pH 8.0. The Km for iodide and SAM were 12 mM and 12 μM, respectively, which were measured using a partially purified enzyme. Various metal ions had no significant effect on methyl iodide production, suggesting that the enzyme does not require metal ions. The enzyme reaction strictly depended on SAM as a methyl donor, and the enzyme catalyzed methylation of the I-, Br-, and Cl- to corresponding monohalomethanes and of bisulfide to methyl mercaptan.
通过阴离子交换、
羟基磷灰石和凝胶过滤两种色谱法,从海洋微藻 Pavlova pinguis 中纯化出了一种产生单卤
甲烷的酶--
S-腺苷-L-蛋氨酸依赖性卤离子甲基转移酶(
EC 2.1.1.-)。甲基转移酶为单体分子,分子量为 29 000。该酶的等电点为 5.3,在 pH 值为 8.0 时活性最佳。使用部分纯化的酶测得
碘化物和 S
AM 的 Km 值分别为 12 mM 和 12 μM。各种
金属离子对
碘甲烷的生成没有明显影响,这表明该酶不需要
金属离子。该酶反应严格依赖于 S
AM 作为甲基供体,该酶催化 I-、Br- 和 Cl-甲基化为相应的单卤代
甲烷,催化二
硫化物甲基化为
甲硫醇。