THE FINAL STEP IN METHANE FORMATION - INVESTIGATIONS WITH HIGHLY PURIFIED METHYL-COM REDUCTASE (COMPONENT-C) FROM METHANOBACTERIUM-THERMOAUTOTROPHICUM (STRAIN MARBURG)
THE FINAL STEP IN METHANE FORMATION - INVESTIGATIONS WITH HIGHLY PURIFIED METHYL-COM REDUCTASE (COMPONENT-C) FROM METHANOBACTERIUM-THERMOAUTOTROPHICUM (STRAIN MARBURG)
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DOI：
10.1111/j.1432-1033.1988.tb13941.x
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发表时间：
1988-03-15
期刊：
影响因子：
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通讯作者：
THAUER, RK
中科院分区：
文献类型：
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作者：
ELLERMANN, J;HEDDERICH, R;THAUER, RK
通过厌氧快速蛋白质液相色谱法在Mono Q和Superose 6柱上高度纯化来自热自养甲烷杆菌（马尔堡菌株）的甲基辅酶M还原酶（=组分C）。发现该酶催化甲基辅酶M（CH 3-S-CoM）与N-7-巯基庚酰基苏氨酸磷酸（H-S-HTP =组分B）还原为CH 4。H-S-CoM和H-S-HTP的混合二硫化物（CoM-S-S-HTP）是形成的另一种主要产物。比活性高达75 nmol min-1 mg protein-1。在二硫苏糖醇和还原的类可丽素或柠檬酸钛（III）的存在下，用H-S-HTP将CH 3-S-CoM还原为CH 4的比速率增加至0.5-2 μ mol min-1 mg蛋白质-1。在这些条件下，由CH 3-S-CoM和H-S-HTP形成的CoM-S-S-HTP被完全还原为H-S-CoM和H-S-HTP。甲基辅酶M还原酶对H-S-HTP具有专一性。N-6-巯基己酰苏氨酸磷酸（H-S-HxoTP）和N-8-巯基辛酰苏氨酸磷酸（H-S-OcoTP）以及任何其他硫醇化合物都不能取代H-S-HTP。相反，发现H-S-HxoTP（表观Ki = 0.1 μ M）和H-S-OcoTP（表观Ki = 15 μ M）是甲基-CoM还原酶的有效抑制剂，抑制作用与CH 3-S-CoM是非竞争性的，而与H-S-HTP是竞争性的。
Methyl-coenzyme M reductase (= component C) from Methanobacterium thermoautotrophicum (strain Marburg) was highly purified via anaerobic fast protein liquid chromatography on columns of Mono Q and Superose 6. The enzyme was found to catalyze the reduction of methylcoenzyme M (CH3-S-CoM) with N-7-mercaptoheptanoylthreonine phosphate (H-S-HTP = component B) to CH4. The mixed disulfide of H-S-CoM and H-S-HTP (CoM-S-S-HTP) was the other major product formed. The specific activity was up to 75 nmol min-1 mg protein-1. In the presence of dithiothreitol and of reduced corrinoids or titanium(III) citrate the specific rate of CH3-S-CoM reduction to CH4 with H-S-HTP increased to 0.5-2 .mu.mol min-1 mg protein-1. Under these conditions the CoM-S-S-HTP formed from CH3-S-CoM and H-S-HTP was completely reduced to H-S-CoM and H-S-HTP. Methyl-CoM reductase was specific for H-S-HTP as electron donor. Neither N-6-mercaptohexanoylthreonine phosphate (H-S-HxoTP) nor N-8-mercaptooctanoylthreonine phosphate (H-S-OcoTP) nor any other thiol compound could substitute for H-S-HTP. On the contrary, H-S-HxoTP (apparent Ki = 0.1 .mu.M) and H-S-OcoTP (apparent Ki = 15 .mu.M) were found to be effective inhibitors of methyl-CoM reductase, inhibition being non-competitive with CH3-S-CoM and competitive with H-S-HTP.