Electron acquisition system constructed from an NAD-independent D-lactate dehydrogenase and cytochrome c2 in Rhodopseudomonas palustris no. 7
Electron acquisition system constructed from an NAD-independent D-lactate dehydrogenase and cytochrome c2 in Rhodopseudomonas palustris no. 7
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DOI：
10.1271/bbb.68.516
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发表时间：
2004-03-01
影响因子：
1.6
通讯作者：
Fujii, T
中科院分区：
文献类型：
--
作者：
Horikiri, S;Aizawa, Y;Fujii, T
本文测定了光厌氧培养的沼泽红球藻7号（Rhodopyruspalustris No.7）的NAD非依赖性D-和L-乳酸脱氢酶（D-LDH、L-LDH）活性。这些酶之一，D-LDH，被纯化为一种同源蛋白质（M-r，约235，000;亚基M-r约57，000）。pI为5.0。该酶的最适pH为8.5，最适温度为50 ℃。该酶对D-乳酸的Km为0.8mm，对D-乳酸和DL-2-羟基丁酸的底物专一性较窄。酶活性竞争抑制草酸（Ki，0.12毫米）。该酶含有FAD辅因子。细胞色素c（2）是从7号菌株中纯化的一种电泳均一蛋白。其pI为9.4。细胞色素c（2）与D-乳酸脱氢酶（LDH）和D-乳酸孵育后被还原。
The activities of NAD-independent D- and L-lactate dehydrogenases (D-LDH, L-LDH) were detected in Rhodopseudomonas palustris No. 7 grown photoanaerobically on lactate. One of these enzymes, D-LDH, was purified as an electrophoretically homogeneous protein (M-r, about 235,000; subunit M-r about 57,000). The pI was 5.0. The optimum pH and temperature of the enzyme were pH 8.5 and 50degreesC, respectively. The Km of the enzyme for D-lactate was 0.8 mm. The enzyme had narrow substrate specificity (D-lactate and DL-2-hydroxy-butyrate). The enzymatic activity was competitively inhibited by oxalate (Ki, 0.12 mm). The enzyme contained a FAD cofactor. Cytochrome c(2) was purified from strain No. 7 as an electrophoretically homogeneous protein. Its pI was 9.4. Cytochrome c(2) was reduced by incubating with D-LDH and D-lactate.