Matsushita K, Yamamoto T, Toyama H, Adachi O
a Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University.
Biosci Biotechnol Biochem. 1998;62(10):1968-77. doi: 10.1271/bbb.62.1968.
The respiratory chain of Corynebacterium glutamicum was investigated, especially with respect to a cyanide-resistant respiratory chain bypass oxidase. The membranes of C. glutamicum had NADH, succinate, lactate, and NADPH oxidase activities, and menaquinone, and cytochromes a 598, b 562(558), and c 550 as respiratory components. The NADH, succinate, lactate, and NADPH oxidase systems, all of which were more cyanide-resistant than N,N,N',N'-tetramethyl-p-phenylene diamine oxidase activity (cytochrome aa 3 terminal oxidase), had different sensitivities to cyanide; the cyanide sensitivity of these oxidase systems increased in the order, NADPH, lactate, NADH, and succinate. Taken together with the analysis of redox kinetics in the cytochromes and the effects of respiratory inhibitors, the results suggested that there is a cyanide-resistant bypass oxidase branching at the menaquinone site, besides cyanide-sensitive cytochrome oxidase in the respiratory chain. H(+)/O measurements with resting cells suggested that the cyanide-sensitive respiratory chain has two or three coupling sites, of which one is in NADH dehydrogenase and the others between menaquinone and cytochrome oxidase, but the cyanide-resistant bypass oxidase may not have any proton coupling site. NADPH and lactate oxidase systems were more resistant to UV irradiation than other systems and the UV insensitivity was highest in the NADPH oxidase system, suggesting that a specific quinone resistant to UV or no such a quinone works in at least NADPH oxidase system while the UV-sensitive menaquinone pool does in other oxidase systems. Furthermore, superoxide was generated in well-washed membranes, most strongly in the NADPH oxidase system. Thus, it was suggested that the cyanide-resistant bypass oxidase system of C. glutamicum is related to the NADPH oxidase system, which may be involved in generation of superoxide anions and probably functions together with superoxide dismutase and catalase.
对谷氨酸棒杆菌的呼吸链进行了研究，特别是关于一种抗氰呼吸链旁路氧化酶。谷氨酸棒杆菌的细胞膜具有NADH、琥珀酸、乳酸和NADPH氧化酶活性，以及作为呼吸成分的甲萘醌和细胞色素a 598、b 562（558）和c 550。NADH、琥珀酸、乳酸和NADPH氧化酶系统，所有这些系统都比N，N，N'，N'-四甲基对苯二胺氧化酶活性（细胞色素aa 3末端氧化酶）更抗氰，对氰化物具有不同的敏感性；这些氧化酶系统对氰化物的敏感性按NADPH、乳酸、NADH和琥珀酸的顺序增加。结合细胞色素中氧化还原动力学的分析和呼吸抑制剂的作用，结果表明，除了呼吸链中对氰化物敏感的细胞色素氧化酶外，在甲萘醌位点还有一个抗氰旁路氧化酶分支。对静息细胞进行的H(+)/O测量表明，对氰化物敏感的呼吸链有两个或三个偶联位点，其中一个在NADH脱氢酶中，其他的在甲萘醌和细胞色素氧化酶之间，但抗氰旁路氧化酶可能没有任何质子偶联位点。NADPH和乳酸氧化酶系统比其他系统对紫外线照射更具抗性，并且在NADPH氧化酶系统中紫外线不敏感性最高，这表明至少在NADPH氧化酶系统中有一种对紫外线抗性的特定醌或不存在这样的醌起作用，而在其他氧化酶系统中是对紫外线敏感的甲萘醌库起作用。此外，在充分洗涤的细胞膜中产生了超氧化物，在NADPH氧化酶系统中产生得最强。因此，有人提出谷氨酸棒杆菌的抗氰旁路氧化酶系统与NADPH氧化酶系统有关，后者可能参与超氧阴离子的产生，并且可能与超氧化物歧化酶和过氧化氢酶一起发挥作用。
