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Structures and Reactivities of Quaternary Metal Complexes as Enzyme Models

作为酶模型的四元金属配合物的结构和反应性

基本信息

批准号：
02453039
负责人：
YAMAUCHI Osamu
金额：
$ 3.26万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02453039/
关键词：
Enzyme model metal complex Quaternary metal complex Ligand-ligand interaction Aromatic ring stacking Pterin-Cu (II) complex Tetrahydropterin Pt (II) complex containing an aromatic ring DNA-intercalator adduct model 四元錯体形成反応安定度定数プテリン含

项目摘要

With a view to elucidating the structures and reaction mechanisms of metalloenzyme-cofactor-substrate intermediate complexes, we investigated the structures, stabilities, and reactivities of ternary and quaternary complex systems as biological models.1. Aromatic ring stacking in ternary Cu (II) complexes, [Cu (bpy) (L-Trp) ClO_4]and[Cu (bpy) (L-Tyr)ClO_4]・2H_2O (bpy = 2, 2'-bipyridine ; Trp =tryptophan ; Tyr = tyrosine), has been established in the solid state between bpy and the side chain aromatic ring of Trp and Tyr, respectively, by X-ray crystal structure analysis. Upon phosphorylation of the Tyr phenol OH group, the phenol ring is involved in electrostatic interactions with the charged side group of arginine or lysine coordinated to the same Cu (II) ion. The result suggests the possibility that Tyr phosphorylation in proteins causes the change in the mode of interactions between the side chain groups of amino acid residues and thus gives rise to protein conformational changes.2. … More Adduct formation between platinum DNA intercalators[Pt (L) (en)] (L = bpy, 1, 10-phenanthroline (plien), 3, 4, 7, 8tetramethyl-1, 10-phenanthroline (Me_4phen) ) and mononucleotides (NMP = AMP, GMP, CMP) has been studied by spectroscopic methods. [pt (Me_4phen) (en)]with the largest hydrophobic area has been found to form the most stable adducts with NMP mainly through the stacking between L and the base moiety of NMP. It was concluded that the electrostatic interactions between the NMP phosphate group and Pt^<2+> or the coordinated en NH_2 group contribute to the adduct stability.3. Structures and stabilities of ternary and quaternary Cu (II) complexes involving a pterin cofactor model have been investigated by spectroscopic methods and potentiometry. Cu (bpy) (PC) (PC pterin-6-carboxylate) as a phenylalanine hydroxylase active site model was found to form quaternary complexes with L = imidazole (im), NH_3, or N_3^-, and the stability constants for the Cu (bpy) (PC) (im) system were successfully detemined by pH titrations at 25ﾟC and I = 0.1 M (KNO_3). The redox reactions between Cu (bpy)^<2+> and a tetrahydropterin were followed by spectroscopic and chromatographic methods, which revealed that the pterin is oxided to the dihydro form with, consumption of dioxygen. Less

为了阐明金属酶-辅因子-底物中间体复合物的结构和反应机理，我们研究了作为生物模型的三元和四元复合物体系的结构、稳定性和反应活性.通过X射线晶体结构分析，确定了Cu（II）三元配合物[Cu（bpy）（L-Trp）ClO_4]和[Cu（bpy）（L-Tyr）ClO_4]·2H_2O（bpy = 2，2 '-联吡啶; Trp =色氨酸; Tyr =酪氨酸）在固态下分别与Trp和Tyr的侧链芳环之间存在芳环堆积。在Tyr苯酚OH基团的磷酸化后，苯酚环参与与配位至相同Cu（II）离子的精氨酸或赖氨酸的带电侧基的静电相互作用。这一结果表明，蛋白质中Tyr的磷酸化可能导致氨基酸残基侧链基团之间相互作用方式的改变，从而引起蛋白质构象的变化. ...更多信息用光谱法研究了铂DNA嵌入剂[Pt（L）（en）]（L = bpy，1，10-菲咯啉（plien），3，4，7，8-四甲基-1，10-菲咯啉（Me_4phen））与单核苷酸（NMP = AMP，GMP，CMP）的加合反应。[pt疏水面积最大的[（Me_4phen）（en）]与NMP形成最稳定的加合物，主要是通过L与NMP碱基的堆积作用。结果表明，NMP磷酸酯基团与Pt^2+或NH_2配位基团之间的静电相互作用有助于加合物的稳定性.用光谱法和电位法研究了含蝶呤辅因子模型的三元和四元Cu（II）配合物的结构和稳定性。Cu（bpy）（PC）（PC蝶呤-6-羧酸酯）作为苯丙氨酸羟化酶活性中心模型，与L =咪唑（im）、NH_3或N_3 ~-形成四元配合物，并在25 ℃、I = 0.1M（KNO_3）下用pH滴定法测定了Cu（bpy）（PC）（im）体系的稳定常数。通过光谱和色谱方法跟踪Cu（bpy）^<2+>和四氢蝶呤之间的氧化还原反应，结果表明蝶呤被氧化为二氢形式，消耗分子氧。少