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首页> 外文期刊>Journal of Inorganic Biochemistry: An Interdisciplinary Journal >Copper(II)-dipeptide complexes containing an acidic and a basic amino acid residue. Side chain effects on structures and stabilities
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Copper(II)-dipeptide complexes containing an acidic and a basic amino acid residue. Side chain effects on structures and stabilities

机译：含有酸性和碱性氨基酸残基的铜（II）-二肽配合物。侧链对结构和稳定性的影响

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摘要

The structures and stability constants of the copper(II) complexes of dipeptides (L) composed of N-terminal arginine (Arg), lysine (Lys) or glycinate (Gly), and C-terminal aspartate (Asp), glutamate (Glu) or Gly have been investigated by X-ray crystallographic,. potentiometric and spectroscopic methods. The molecular structures of Cu(II)-arginylaspartate and -arginylglutamate both with the deprotonated peptide nitrogen, [Cu(ArgAspH_(-1))] centre dot H_2O (1) and [Cu(ArgGluH_(-1))] centre dot 4H_2O (2), respectively, were determined to have the dipeptides coordinated in the equatorial positions through the two nitrogen atoms and an oxygen atom from the #beta#-carboxylate group in 1 and the #alpha#-carboxylate group in 2. The #alpha#- and #gamma#-carboxylate oxygen atoms in 1 and 2, respectively, bind with neighboring complex molecules to form a bridge and complete the Cu(II) coordination plane. The bridge formation was supported by the concentration dependence of the electron spin resonance (ESR) spectra. The stability constants for proton-L and 1:1 Cu(II)-L systems were determined at 5, 25 and 37 deg C(I=0.1 M KNO_3), and the relevant thermodynamic parameters were calculated by using the van't Hoff equation. The stabilities of CuL and Cu(LH_(-1)) were found to be in the order XAsp >= XGlu > XGly (X = Arg, Lys or Gly), indicating that the C-terminal Asp residue enhances the stability. From the thermodynamic parameters obtained, the interactions between the oppositely charged side chains in Cu(II)-coordinated XY (X=Arg, Lys; Y=Asp, Glu) have been discussed.
机译：由N端精氨酸（Arg），赖氨酸（Lys）或甘氨酸（Gly）和C端天冬氨酸（Asp），谷氨酸（Glu）组成的二肽（L）的铜（II）配合物的结构和稳定性常数X射线晶体学已经研究了Gly或Gly。电位计和光谱法。带有去质子化肽氮，[Cu（ArgAspH _（-1））]中心点H_2O（1）和[Cu（ArgGluH _（-1））]中心点4H_2O的Cu（II）-精氨酸谷氨酸和-精氨酸谷氨酸的分子结构分别确定（2）中的二肽在赤道位置通过两个氮原子和一个氧原子（分别来自1中的＃beta＃-羧酸酯基和2中的＃alpha＃-羧酸酯基）。 1和2中的＃-和＃γ＃-羧基氧原子与相邻的复合分子结合形成桥并完成Cu（II）配位平面。电子自旋共振（ESR）光谱的浓度依赖性支持了电桥的形成。确定质子L和1：1 Cu（II）-L系统在5、25和37摄氏度（I = 0.1 M KNO_3）时的稳定性常数，并使用van't Hoff计算相关的热力学参数方程。发现CuL和Cu（LH _（-1））的稳定性为XAsp> = XGlu> XGly（X = Arg，Lys或Gly），表明C末端的Asp残基增强了稳定性。从获得的热力学参数，讨论了在Cu（II）配位的XY（X = Arg，Lys; Y = Asp，Glu）中带相反电荷的侧链之间的相互作用。

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