Stereoselective ligand interactions of chicken liver phosphoenolpyruvate carboxykinase with fluorophosphoenolpyruvate.
Stereoselective ligand interactions of chicken liver phosphoenolpyruvate carboxykinase with fluorophosphoenolpyruvate.
复制标题
鸡肝磷酸烯醇丙酮酸羧激酶与氟磷酸烯醇丙酮酸的立体选择性配体相互作用。
DOI：
10.1016/0003-9861(89)90150-1
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发表时间：
1989
影响因子：
3.9
通讯作者：
Nowak,T
中科院分区：
文献类型：
--
作者：
Hwang,SH;Nowak,T
研究了鸡肝磷酸烯醇式丙酮酸羧激酶（P-enolpyruvate carboxkinase）与3-氟磷酸烯醇式丙酮酸（F-P-enolpyruvate）两种几何异构体的立体专一性相互作用。以前的研究表明，F-β-烯醇丙酮酸的Z异构体是β-烯醇丙酮酸羧激酶的底物，而E异构体是竞争性抑制剂[T. H. Duffy和T. Nowak（1984）Biochemistry 23，661-670]。这种底物选择性的原因进行了研究。对Mn-配体二元配合物中配体的~ 1H、~（19）F和~（31）P弛豫速率的研究表明，形成了直接配位配合物。质子弛豫速率（PRR）的温度和频率的依赖性的相应的酶锰配体复合物表明，在Mn（II）的网站上的酶的电子环境的扰动是不同的抑制剂（E-F-P-烯醇丙酮酸）的结合后，相反的结合底物（P-烯醇丙酮酸或Z-F-P-烯醇丙酮酸）。结构研究表明，Z-F-P-烯醇式丙酮酸与酶结合的Mn（II）形成第二球配位复合物。E-F-P-烯醇式丙酮酸从三元复合物中缓慢交换，并与结合的Mn（II）结合10 Å。远紫外区的圆二色性研究表明，当Mn（Ⅱ）和底物（β-烯醇式丙酮酸或Z-F-β-烯醇式丙酮酸）与脱辅基酶结合时，β-烯醇式丙酮酸羧激酶的α-螺旋含量增加，而反平行和平行β-折叠结构减少，但Mn（Ⅱ）和E-F-β-烯醇式丙酮酸结合时，α-螺旋结构没有变化。在芳香族氨基酸区域（250-350 nm）的CD研究中观察到类似的结果。β-烯醇丙酮酸羧激酶与F-P-烯醇丙酮酸类似物的立体选择性催化活性可以通过这些配体在酶的催化位点内的不同相互作用来解释。
The stereospecific interactions of chicken liver phosphoenolpyruvate carboxykinase (P-enolpyruvate carboxykinase) with the two geometric isomers of 3-fluorophosphoenolpyruvate (F-P-enolpyruvate) were examined. Previous studies have shown that theZisomer of F-P-enolpyruvate is a substrate for P-enolpyruvate carboxykinase but theEisomer is a competitive inhibitor [T. H. Duffy and T. Nowak (1984)Biochemistry23, 661–670]. The reasons for this substrate selectivity were investigated. Studies of the1H,19F, and31P relaxation rates of the ligands in the binary Mn-ligand complexes indicate the formation of direct coordination complexes. The temperature and frequency dependence of the proton relaxation rates (PRR) of the respective enzyme-Mn-ligand complexes demonstrates that the perturbation of the electronic environment at the Mn(II) site on the enzyme is different upon binding of the inhibitor (E-F-P-enolpyruvate) in contrast to the binding of substrates (P-enolpyruvate orZ-F-P-enolpyruvate). Structural studies demonstrate thatZ-F-P-enolpyruvate forms a second sphere coordination complex with enzyme-bound Mn(II).E-F-P-enolpyruvate exchanges slowly from the ternary complex and binds ⩽ 10 Å from the bound Mn(II). CD studies in the far-uv region demonstrate that the α-helical content of P-enolpyruvate carboxykinase is increased at the expense of antiparallel and parallel β-sheet structure upon binding of Mn(II) and substrate (P-enolpyruvate orZ-F-P-enolpyruvate) to the apoenzyme, but show no such structural change upon binding of Mn(II) andE-F-P-enolpyruvate. Analogous results are observed from CD studies at the aromatic amino acid region (250–350 nm). The stereoselective catalytic activities of P-enolpyruvate carboxykinase with F-P-enolpyruvate analogs can be explained by different interactions of these ligands within the catalytic site of the enzyme.