Zinc complexation of glutathione and glutathione-derived peptides
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- 作者：Gelinsky ; M. ; Vogler ; R. ; Vahrenkamp ; H.
- 关键词：Zinc complexes ; Glutathione complexes ; Peptide complexes
- 刊名：Inorganica Chimica Acta
- 出版年：2003
- 出版时间：February 20, 2003
- 年：2003
- 卷：344
- 期：Complete
- 页码：230-238
- 全文大小：212 K
文摘
Glutathione (γ-Glu-Cys-Gly, GSH, 1) forms a binary zinc complex of the type L2Zn3 (1.1) which is polymeric. Its triply blocked and purely S-functional form [4-NO2
Bz]-γ-Glu(Cys-Gly-OEt)-OEt (2) yields a polymeric complex of the type L2Zn (2.1) and a monomeric pyrazolylborate zinc complex of the type TpZnSR (2.2). Doubly O-protected GSH was converted with histidine and cysteine to the difunctional tetrapeptides NAc-His-γ-Glu(Cys-Gly-OEt)-OEt (3) and NAc-Cys-γ-Glu(Cys-Gly-OEt)-OEt (4). Peptide 3 could be converted to the oligomeric zinc halide complex of the type L·ZnCl (3.1). The zinc complexation of peptide 4 was investigated by potentiometric titrations, revealing that the dominating species in solution are [ZnL(LH)]− and [ZnL2]2−, both with a ZnS4 coordination. In contrast, the isolated complex was found to be the polymeric species of composition LZn (4.1). With pyrazolylborate zinc units a monomeric dizinc complex of the type TpZnS
SZnTp (4.2) was obtained. N-protected GSH was extended by two histidine or cysteine units to the pentapeptides H-γ-Glu(Cys-Gly-His-OMe)-His-OMe (5) and H-γ-Glu(Cys-Gly-Cys-OMe)-Cys-OMe (6). Complex 5 and 6 formed ill-defined polymeric zinc complexes. For 5 a species of the type [L·Zn]ClO4 and for 6 a species of the type [L3Zn5]CF3COO could be obtained analytically pure.
Bz]-γ-Glu(Cys-Gly-OEt)-OEt (2) yields a polymeric complex of the type L2Zn (2.1) and a monomeric pyrazolylborate zinc complex of the type TpZnSR (2.2). Doubly O-protected GSH was converted with histidine and cysteine to the difunctional tetrapeptides NAc-His-γ-Glu(Cys-Gly-OEt)-OEt (3) and NAc-Cys-γ-Glu(Cys-Gly-OEt)-OEt (4). Peptide 3 could be converted to the oligomeric zinc halide complex of the type L·ZnCl (3.1). The zinc complexation of peptide 4 was investigated by potentiometric titrations, revealing that the dominating species in solution are [ZnL(LH)]− and [ZnL2]2−, both with a ZnS4 coordination. In contrast, the isolated complex was found to be the polymeric species of composition LZn (4.1). With pyrazolylborate zinc units a monomeric dizinc complex of the type TpZnSSZnTp (4.2) was obtained. N-protected GSH was extended by two histidine or cysteine units to the pentapeptides H-γ-Glu(Cys-Gly-His-OMe)-His-OMe (5) and H-γ-Glu(Cys-Gly-Cys-OMe)-Cys-OMe (6). Complex 5 and 6 formed ill-defined polymeric zinc complexes. For 5 a species of the type [L·Zn]ClO4 and for 6 a species of the type [L3Zn5]CF3COO could be obtained analytically pure.