Reaction of myoglobin with phenylhydrazine: a molecular doorstop.
Reaction of myoglobin with phenylhydrazine: a molecular doorstop.
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肌红蛋白与苯肼的反应：分子门挡。
DOI：
10.1021/bi00296a001
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发表时间：
1984
期刊：
影响因子：
2.9
通讯作者：
OrtizdeMontellano,PR
中科院分区：
文献类型：
--
作者：
Ringe,D;Petsko,GA;Kerr,DE;OrtizdeMontellano,PR
Dagmar Ringe,* Gregory A. Petsko, David E. Kerr和Paul R. Ortiz de Montellano摘要：肌红蛋白的x射线晶体学研究没有显示从表面到血红素腔的潜在配体的入口或出口路径。到目前为止，寻找这样一条路径的努力都集中在动态计算上。现在已经确定了一个结构，它有一个清晰的开口。苯肼与肌红蛋白发生反应，使苯基。根据x射线衍射测定的肌红蛋白三维结构（Kendrew et al., 1960; Perutz & Matthews, 1966; Nobbs, 1966; Takano, 1977a, b），潜在配体从蛋白质外部进入远端血红素“口袋”没有明显的入口或出口路径。事实上，对脱氧肌红蛋白和配体肌红蛋白结构的检查表明，血红素袋对配体的可及性被几种氨基酸的侧链所阻断。已经提出了许多关于结构变化的建议，这些变化将形成通往配体结合位点的路径，其中许多涉及e -螺旋部分的波动。例如，His-64 （E7）的旋转，随后是Arg-45 （CD3）侧链的运动，将允许配体进入（Nobbs, 1966）。然而，这种运动至今还没有出现。咪唑与肌红蛋白结合导致晶体b轴长度的延长（Nobbs, 1966）。这被解释为His-64 （E7）和Arg-45 （CD3）被迫离开其正常位置以适应配体。轨迹和能量最小化计算表明His-64 （E7）和Val-68 （E11）位于大潜力井中（Case & Karplus, 1979）。此外，Val-68 （E11）的参与与甲基核磁共振对pH值的依赖、阴离子的结合以及与铁结合的配体的性质有关（Lindstrom & Ho, 1973）。因此，假设了两条主要途径，其中以下氨基酸残基对能量势垒起主要作用。对于经典路径，His-64 (E7), Thr-67 （E10）和Val-68 （E11）是重要的残基。在次级路径中，Leu-61 （E4）和ph -34-(B14)是重要的残基。通过x射线衍射对肌红蛋白结构的动力学研究（Frauenfelder et al., 1979）表明没有
Dagmar Ringe,* Gregory A. Petsko, David E. Kerr, and Paul R. Ortiz de Montellano abstract: X-ray crystallographic studies of myoglobin do not show an entrance or exit path for potential ligands from the surface to the heme cavity. Efforts to locate such a path have so far centered around dynamic calculations. A structure has now been determined that has a clear opening. Phenylhydrazine reacts with myoglobin in such a way that a phenyl.^^. ccording to the three-dimensional structures of myoglobin determined by X-ray diffraction (Kendrew et al., 1960; Perutz & Matthews, 1966; Nobbs, 1966; Takano, 1977a, b), there is no obvious entrance or exit path for potential ligands from the outside of the proteininto the distal heme “pocket”. In fact, examination of the structures of deoxymyoglobin and liganded myoglobin has indicated that accessibility of the heme pocket to ligands is blocked by the side chains of several amino acids. Numerous suggestions have been made for structural changes that would form a path to the ligand binding site, many involving fluctuations of parts of the E-helix. For instance, rotation of His-64 (E7), followed by movement of the Arg-45 (CD3) side chain, would allow entry of a ligand (Nobbs, 1966). However, such a movement has as yet not been ob-served. Binding of imidazole to metmyoglobin causes extension of the b-axial length in the crystal (Nobbs, 1966). This has been interpreted to indicate that His-64 (E7) and Arg-45 (CD3) have been forced away from their normal positions to accom-modate the ligand. Trajectory and energy minimization calculations have indicated that His-64 (E7) and Val-68 (E11) lie in broad potential wells (Case & Karplus, 1979). In ad-dition, involvement of Val-68 (E11) is implicated by dependence of the methyl NMR on pH, the bindingof anions, and the nature of the ligand bound to the iron (Lindstrom & Ho, 1973).Consequently, two major paths have been postulated, to which the following amino acid residues make the dominant contributions to the energy barriers. For the classical path, His-64 (E7), Thr-67 (E10), and Val-68 (E11) are the important residues. For the secondary path, Leu-61 (E4) and Phe-34-(B14) are the important residues. A study of the dynamics of the myoglobin structure by X-ray diffraction (Frauenfelder et al., 1979) shows that none