PURIFICATION AND CHARACTERIZATION OF METHIONINE GAMMA-LYASE FROM TRICHOMONAS-VAGINALIS
PURIFICATION AND CHARACTERIZATION OF METHIONINE GAMMA-LYASE FROM TRICHOMONAS-VAGINALIS
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DOI：
10.1042/bj2790675
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发表时间：
1991-11-01
影响因子：
4.1
通讯作者：
COOMBS, GH
中科院分区：
文献类型：
--
作者：
LOCKWOOD, BC;COOMBS, GH
通过一系列f.p.l.c.从厌氧原生动物寄生虫阴道毛滴虫中纯化甲硫氨酸γ-裂解酶（EC 4.4.1.11）至均一。程序. 该酶催化许多甲硫氨酸和半胱氨酸衍生物的α-γ-和α-β-消除反应。 它还催化甲硫氨酸、高半胱氨酸和乙硫氨酸的硫代甲基的γ-置换反应，以产生相应的S-取代的高半胱氨酸衍生物。 该酶是吡哆醛5 '-磷酸盐依赖性的，具有约1000的天然分子量。160 kDa，由四个分子量43-45 kDa的明显相同的亚基组成。 该酶的吸收光谱是其他吡哆醛5 '-磷酸依赖性酶的典型吸收光谱，全酶可通过与羟胺孵育分解为脱辅基酶，并通过加入辅因子进行重组。 的酶活性是显着的羰基和巯基试剂的影响，是竞争性抑制的底物类似物的数量和完全灭活的自杀抑制剂DL-炔丙基甘氨酸。 霸王就活性和性质而言，迷走神经酶类似于在厌氧条件下代谢甲硫氨酸的许多细菌物种中发现的酶。 这表明，蛋氨酸催化剂可能是特别重要的T。在微需氧条件下的迷走神经。
Methionine gamma-lyase (EC 4.4.1.11) was purified to homogeneity from the anaerobic protozoan parasite Trichomonas vaginalis by a series of f.p.l.c. procedures. The enzyme catalyses alpha-gamma- and alpha-beta-elimination reactions of a number of derivatives of methionine and cysteine. It also catalyses gamma-replacement reactions of the thiomethyl group of methionine, homocysteine and ethionine to yield the corresponding S-substituted homocysteine derivative. The enzyme is pyridoxal 5'-phosphate-dependent, has a native molecular mass of approx. 160 kDa and consists of four apparently identical subunits of molecular mass 43-45 kDa. The absorption spectrum of the enzyme is typical of those obtained for other pyridoxal 5'-phosphate-dependent enzymes, and the holoenzyme can be resolved to the apoenzyme by incubation with hydroxylamine and reconstituted by addition of the cofactor. The enzyme activity is significantly affected by carbonyl and thiol reagents, is competitively inhibited by a number of substrate analogues and is completely inactivated by the suicide inhibitor DL-propargylglycine. The T. vaginalis enzyme is similar, in terms of activity and properties, to the enzymes found in a number of species of bacteria that metabolize methionine under anaerobic conditions. It is suggested that methionine catabolism may be of particular importance to the survival of T. vaginalis under microaerophilic conditions in its host.