Carboxylation reaction catalyzed by 2-oxoglutarate:ferredoxin oxidoreductases from Hydrogenobacter thermophilus
Carboxylation reaction catalyzed by 2-oxoglutarate:ferredoxin oxidoreductases from Hydrogenobacter thermophilus
复制标题
2-酮戊二酸催化的羧化反应：来自嗜热氢杆菌的铁氧还蛋白氧化还原酶
DOI：
10.1007/s00792-009-0289-4
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发表时间：
2009
期刊：
影响因子：
2.9
通讯作者：
Y. Igarashi
中科院分区：
文献类型：
--
作者：
Masahiro Yamamoto;T. Ikeda;H. Arai;M. Ishii;Y. Igarashi
嗜热嗜氢菌TK-6是一种嗜热、化能自养、氢氧化细菌，通过还原性三羧酸（rTCA）循环固定二氧化碳。2-酮戊二酸：铁氧还蛋白氧化还原酶（OGOR）是这个循环中固定二氧化碳的关键酶。菌株TK-6的基因组编码至少两种不同的OGOR酶，称为For和Kor。我们在这里报告的方法，用于测量琥珀酰辅酶A的羧化催化的OH 3。该方法涉及OGOR与铁氧还蛋白和丙酮酸的体外偶联：来自菌株TK-6的铁氧还蛋白氧化还原酶和来自东京硫化叶菌的谷氨酸脱氢酶。使用该方法，我们确定了琥珀酰辅酶A羧化的表观最大速度和For和Kor的Km值。这是第一次报道的OGOR酶催化的碳固定的rTCA循环的动力学分析。
Hydrogenobacter thermophilus TK-6 is a thermophilic, chemolithoautotrophic, hydrogen-oxidizing bacterium that fixes carbon dioxide via the reductive tricarboxylic acid (rTCA) cycle. 2-Oxoglutarate:ferredoxin oxidoreductase (OGOR) is the key enzyme in this cycle that fixes carbon dioxide. The genome of strain TK-6 encodes at least two distinct OGOR enzymes, termed For and Kor. We report here a method for measuring the carboxylation of succinyl-CoA catalyzed by OGORs. The method involves the in vitro coupling of OGOR with ferredoxin and pyruvate:ferredoxin oxidoreductase from strain TK-6, and glutamate dehydrogenase from Sulfolobus tokodaii. Using this method, we determined both the apparent maximum velocities and the Km values of For and Kor for the carboxylation of succinyl-CoA. This is the first reported kinetic analysis of carbon fixation catalyzed by OGOR enzymes from the rTCA cycle.