Metallocyclopeptide complexes with MII(S.Cys)4 chromophores.
Metallocyclopeptide complexes with MII(S.Cys)4 chromophores.
复制标题
金属环肽与 MII(S.Cys)4 发色团的复合物。
DOI：
10.1021/ic990421l
复制
发表时间：
2000
影响因子：
4.6
通讯作者：
Holm,RH
中科院分区：
文献类型：
--
作者：
Nivorozhkin,AL;Segal,BM;Musgrave,KB;Kates,SA;Hedman,B;Hodgson,KO;Holm,RH
在PAL−PEG−PS载体上，采用Fmoc/t-Bu/烯丙基策略，采用固相法合成了四胱氨酸肽decyclo[lys1,12](gln -Cys- gly - val -Cys- gys -Cys- ile - al-Cys- lys)（∧L(Cys·SH)4）。用分光光度法观察了M = Fe2+、Co2+和Ni2+在pH为7.5的水溶液中形成的1:1配合物。粒径隔离层析表明，肽为单体，配合物为二聚体[M2(∧L(Cys·S)4)2]，水溶液缓冲液pH为7.5。报道了作为冻干固体的[Co2(∧L(Cys·S)4)2]和[Ni2(∧L(Cys·S)4)2]的钴和镍k边x射线吸收数据和EXAFS分析。得到的键距为Co−S = 2.30 Å和Ni−S = 2.21 Å。从吸收光谱、k边、EXAFS和与已知结构的键长比较所提供的集体结果来看，[Fe2(∧L(Cys·S)4)2]和[Co2(∧L(Cys·S)4)2]具有扭曲的四面体结构，[Ni2(∧L(Cys·S)4)2]具有扭曲的方形平面立体化学。Co（II）发色团在指定结构上特别独特，显示了母体四面体配体场过渡的三个组分：4a2→4T1(P) （610, 685,740 nm）。所观察到的结构符合金属离子固有的立体化学偏好。提出了双核配合物的结构。这是第一个表征的半胱氨酸环肽的金属配合物，也是少数有充分记录的合成环肽配合物之一。这项研究是设计单核和多核金属中心结合的环肽的理想的第一步。
The tetracysteinyl peptidecyclo[Lys1,12](Gln-Cys-Gly-Val-Cys-Gly-Lys-Cys-Ile-Ala-Cys-Lys) (⊂L(Cys·SH)4) was synthesized by solid-phase methods using an Fmoc/t-Bu/allyl strategy on a PAL−PEG−PS support. The formation of the 1:1 complexes with M = Fe2+, Co2+, and Ni2+was observed by spectrophotometric monitoring of reactions in aqueous solution at pH 7.5. Size exclusion chromatography indicated that the peptide is a monomer and the complexes are dimers [M2(⊂L(Cys·S)4)2] in aqueous buffer at pH 7.5. Cobalt and nickel K-edge X-ray absorption data and EXAFS analysis of [Co2(⊂L(Cys·S)4)2] and [Ni2(⊂L(Cys·S)4)2] as lyophilized solids are reported. Derived bond distances are Co−S = 2.30 Å and Ni−S = 2.21 Å. From the collective results provided by absorption spectra, K-edges, EXAFS, and bond length comparisons with known structures, it is shown that [Fe2(⊂L(Cys·S)4)2] and [Co2(⊂L(Cys·S)4)2] possess distorted tetrahedral structures and [Ni2(⊂L(Cys·S)4)2] has distorted square planar stereochemistry. The Co(II) chromophore is particularly distinctive of the assigned structure, displaying three components of the parent tetrahedral ligand field transition4A2→4T1(P) (610, 685, 740 nm). The observed structures conform to the intrinsic stereochemical preferences of the metal ions. Structures for the binuclear complexes are suggested. These are the first characterized metal complexes of a cysteinyl cyclopeptide and among the few well-documented complexes of synthetic cyclopeptides. This study is a desirable first step in the design of cyclic peptides for the binding of mononuclear and polynuclear metal centers.