Jetten M S, Stams A J, Zehnder A J
Department of Microbiology, Agricultural University Wageningen, The Netherlands.
Eur J Biochem. 1989 May 1;181(2):437-41. doi: 10.1111/j.1432-1033.1989.tb14744.x.
Carbon monoxide dehydrogenase was purified to apparent homogeneity from Methanothrix soehngenii. In contrast with the carbon monoxide dehydrogenases from most other anaerobic bacteria, the purified enzyme of Methanothrix soehngenii was remarkably stable towards oxygen and it was only slightly inhibited by cyanide. The native molecular mass of the carbon monoxide dehydrogenase of Methanothrix soehngenii determined by gel filtration was 190 kDa. The enzyme is composed of subunits with molecular mass of 79.4 kDa and 19.4 kDa in an alpha 2 beta 2 oligomeric structure. The enzyme contains 1.9 +/- 0.2 (n = 3) mol Ni/mol and 19 +/- 3 (n = 3) mol Fe/mol and it constitutes 4% of the soluble cell protein. Analysis of enzyme kinetic properties revealed a Km of 0.7 mM for CO and of 65 microM for methyl viologen. At the optimum pH of 9.0 the Vmax was 140 mumol of CO oxidized min-1 mg protein-1. The enzyme showed a high degree of thermostability.
一氧化碳脱氢酶从索氏甲烷丝菌中纯化至表观均一。与大多数其他厌氧细菌的一氧化碳脱氢酶不同，纯化后的索氏甲烷丝菌酶对氧气具有显著的稳定性，仅受到氰化物的轻微抑制。通过凝胶过滤法测定，索氏甲烷丝菌一氧化碳脱氢酶的天然分子量为190 kDa。该酶由分子量分别为79.4 kDa和19.4 kDa的亚基组成，呈α2β2寡聚体结构。该酶含有1.9±0.2（n = 3）mol Ni/mol和19±3（n = 3）mol Fe/mol，占可溶性细胞蛋白的4%。酶动力学性质分析表明，该酶对一氧化碳的Km值为0.7 mM，对甲基紫精的Km值为65 μM。在最适pH 9.0时，Vmax为140 μmol CO氧化·min-1·mg蛋白-1。该酶表现出高度的热稳定性。
