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首页> 外文期刊>Biochemistry >Mutagenesis of Three Conserved Glu Residues in a Bacterial Homologue of the ND1 Subunit of Complex I Affects Ubiquinone Reduction Kinetics but Not Inhibition by Dicyclohexylacarbodiimide
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Mutagenesis of Three Conserved Glu Residues in a Bacterial Homologue of the ND1 Subunit of Complex I Affects Ubiquinone Reduction Kinetics but Not Inhibition by Dicyclohexylacarbodiimide

机译：复杂I的ND1亚基细菌同源物中三个保守Glu残基的诱变影响泛醌还原动力学，但不被二环己基碳二亚胺抑制。

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摘要

Steady-state kinetics of the H~+-translocating NADH:ubiquinone reductase (complex I) were analyzed in membrane samples from bovine mitochondria and the soil bacterium Paracoccus denitrificans.In both enzymes the calculated K_m values,in the membrane lipid phase,for four different ubiquimone analogues were in the millimolar range. Both the structure and size of the hydrophobic side chain of the acceptor affected its affinity for complex I.The ND1 subunit of bovine comples I is a mitochondrially enocoded protein that binds the inhibitor dicyclohexylcarbodiimide (DCCD) covalently [Yagi and Hatefi (1988) J.Biol.Chm.263, 16150-16155].The NQO8 subunit of P.denitrificans comples I is a homologue of ND1,and within it three conserved Glu residues that could bind DCCD,E158,E212,and E247,were changed to either Asp or Gln and in the case of E212 also to Val.The DCCD sensitivity of the resulting mutants was,however,unaffected by the mutations.On the other hand,the ubiquinone reductase activity of the mutants was altered,and the mutations changed the interactions of complex I with short-chain ubiquinones.The implications of the results for the location of the ubiquinone reduction site in this enzyme are discussed.
机译：在牛线粒体和土壤细菌反硝化副球菌的膜样品中分析了H〜+易位的NADH：泛醌还原酶（复合体I）的稳态动力学。两种酶在膜脂质相中计算了四种酶的K_m值不同的泛醌类似物在毫摩尔范围内。受体疏水侧链的结构和大小都会影响其对复合物I的亲和力。牛复合体I的ND1亚单位是线粒体编码的蛋白质，与抑制剂二环己基碳二亚胺（DCCD）共价结合[Yagi和Hatefi（1988）J. Biol.Chm.263，16150-16155]。假单胞菌的NQO8亚基组成I是ND1的同源物，其中三个可以结合DCCD，E158，E212和E247的保守Glu残基被改变为Asp或Gln，在E212的情况下也对Val敏感。然而，所得突变体的DCCD敏感性不受突变影响。另一方面，突变体的泛醌还原酶活性发生了变化，且突变改变了讨论了该酶对泛醌还原位点位置的影响。

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