Purification and Properties of Crystalline 3-Methylaspartase from Two Facultative Anaerobes,<i>Citrobacter</i>sp. Strain YG-0504 and<i>Morganella morganii</i>Strain YG-0601
作者:Yasuo Kato、Yasuhisa Asano
DOI:10.1271/bbb.59.93
日期:1995.1
3-Methylaspartase (3-methylaspartate ammonia-lyase, EC 4.3.1.2) from two facultative anaerobes from soil, Citrobacter sp. strain YG-0504 and Morganella morganii strain YG-0601, were purified and crystallized from their crude extracts. Both of the Citrobacter and Morganella enzymes appeared to be a dimer of subunits of Mr 40,000 and 44,000, respectively. The enzymes had similar enzymological properties: optimum pH for the deamination reaction of (2S, 3S)-3-methylaspartic acid, substrate specificity, inhibitor, divalent and monovalent cation requirement, and N-terminal amino acid sequence homology. However, some differences were detected in pH and temperature stability, optimum pH for the amination reaction of mesaconic acid, optimum temperature, specific activity, and stability during electrophoresis. Both enzymes had similar enzymological properties to the known 3-methylaspartase from an obligate anaerobic bacterium, Clostridium tetanomorphum H1, except kinetic constants and substrate specificities.
从土壤中的两种兼性厌氧菌--柠檬酸杆菌菌株 YG-0504 和摩根氏菌菌株 YG-0601 的粗提取物中纯化并结晶出了 3-甲基天冬氨酸氨水解酶(3-甲基天冬氨酸氨水解酶,EC 4.3.1.2)。柠檬酸杆菌和摩根氏菌的酶似乎都是二聚体,其亚基的摩尔数分别为 40,000 和 44,000。这两种酶具有相似的酶学特性:(2S, 3S)-3-甲基天冬氨酸脱氨反应的最适 pH 值、底物特异性、抑制剂、二价和一价阳离子要求以及 N 端氨基酸序列同源性。然而,在 pH 值和温度稳定性、中酸胺化反应的最适 pH 值、最适温度、特异活性和电泳稳定性方面发现了一些差异。除了动力学常数和底物特异性外,这两种酶的酶学特性与已知的3-甲基天冬氨酸酶(来自一种必须厌氧细菌--四价梭菌H1)相似。