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首页> 外文期刊>Biochemistry >Catalytic Role of the Conformational Change in Succinyl-CoA:3-Oxoacid CoA Transferase on Binding CoA,
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Catalytic Role of the Conformational Change in Succinyl-CoA:3-Oxoacid CoA Transferase on Binding CoA,

机译：琥珀酰-CoA：3-氧代酸CoA转移酶构象变化对结合CoA的催化作用

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Catalysis by succinyl-CoA:3-oxoacid CoA transferase proceeds through a thioester intermediatenin whichCoAis covalently linked to the enzyme. To determine the conformation of the thioester intermediate,ncrystals of the pig enzyme were grown in the presence of the substrate acetoacetyl-CoA.X-ray diffraction datanshow the enzyme in both the free form and covalently bound to CoA via Glu305. In the complex, the proteinnadopts a conformation in which residues 267-275, 280-287, 357-373, and 398-477 have shifted towardnGlu305, closing the enzyme around the thioester. Enzymes provide catalysis by stabilizing the transition statenrelative to complexes with substrates or products. In this case, the conformational change allows the enzymento interact with parts of CoA distant from the reactive thiol while the thiol is covalently linked to the enzyme.nThe enzyme forms stabilizing interactions with both the nucleotide and pantoic acid portions of CoA, whilenthe interactions with the amide groups of the pantetheine portion are poor. The results shed light on how thenenzyme uses the binding energy for groups remote fromthe active center of CoA to destabilize atoms closer tonthe active center, leading to acceleration of the reaction by the enzyme.
机译：琥珀酰-CoA：3-含氧酸CoA转移酶的催化作用是通过硫酯中间体来完成的，其中CoA与该酶共价连接。为了确定硫酯中间体的构象，在底物乙酰乙酰辅酶A的存在下生长了猪酶的n晶体。X射线衍射数据显示该酶呈游离形式，并通过Glu305与CoA共价结合。在复合物中，该蛋白不具有这样的构象，其中残基267-275、280-287、357-373和398-477已移向nGlu305，从而封闭了硫酯周围的酶。酶通过稳定相对于与底物或产物的复合物的过渡态来提供催化作用。在这种情况下，构象变化允许酶与CoA远离反应性硫醇的部分相互作用，而硫醇与酶共价连接.n酶与CoA的核苷酸和泛酸部分均形成稳定相互作用，而与CoA的相互作用泛胺部分的酰胺基很差。该结果揭示了酶如何利用远离CoA活性中心的基团的结合能来破坏靠近活性中心的原子的稳定性，从而促进酶的反应。

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  • 来源
    《Biochemistry》 |2010年第48期|p.10319-10328|共10页
  • 作者

    Marie E. Fraser Koto Hayakawa and William D. Brown;

  • 作者单位

    Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada;

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