复杂的晶体结构不对称的两个核苷酸绑定组件proton-translocating transhydrogenase。
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棉花NP,白色SA,皮克SJ,筹划年代,杰克逊简森-巴顿
复杂的晶体结构不对称的两个核苷酸绑定组件proton-translocating transhydrogenase。
结构。2001年2月7日,9 (2):165 - 76。
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11250201 (在PubMed]
- 文摘
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背景:膜结合离子转运蛋白有重要的生物学功能,但其机制的行动往往知之甚少。Transhydrogenase,发现在动物线粒体和细菌、链接和NAD (H)之间的氧化还原反应是NAD (H)质子跨膜易位。链接是通过核苷酸结合位点的蛋白质构象的变化。两个蛋白质之间的氧化还原反应发生组件位于膜表面:dI,结合NAD (H),和dIII结合NADP (H)第三个组件,dII,提供了一个质子通道通过膜。完整membrane-located transhydrogenase可能是一个二聚体(dI的两个副本,dII dIII)。结果:我们已经解决了dI的高分辨率的晶体结构:dIII复杂的transhydrogenase Rhodospirillum rubrum-the首先从transhydrogenase任何物种。heterotrimer,有两个多肽的dI和dIII之一。dI多肽折叠成一个二聚体。dIII循环,将烟酰胺环是NAD (H),插入的NAD (H)绑定裂dI多肽。 The cleft of the other dI is not occupied by a corresponding dIII component. CONCLUSIONS: The redox step in the transhydrogenase reaction is readily visualized; the NC4 atoms of the nicotinamide rings of the bound nucleotides are brought together to facilitate direct hydride transfer with A-B stereochemistry. The asymmetry of the dI:dIII complex suggests that in the intact enzyme there is an alternation of conformation at the catalytic sites associated with changes in nucleotide binding during proton translocation.