1H n.m.r. conformational studies of glycyl-L-phenylalanine and L-phenylalanyl-glycine dipeptides and their complexes with palladium (II)
1H n.m.r. conformational studies of glycyl-L-phenylalanine and L-phenylalanyl-glycine dipeptides and their complexes with palladium (II)
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1H 核磁共振
DOI：
10.1002/mrc.1270100134
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发表时间：
1977
影响因子：
2
通讯作者：
B. Jeżowska
中科院分区：
文献类型：
--
作者：
H. Kozłowski;G. Formicka;B. Jeżowska
Gly-Phe和Phe-Gly双肽及其与Pd(II)离子的络合物的构象已用1Hn.m.r确定。不同酸碱度范围的光谱。在这两个二肽中最稳定的旋转异构体中，最大的基团，即羧酸盐(或羰基)和芳香环相互转位。在摩尔比为1：1的络合物中，二肽在3-10 pH范围内为三齿配体。在优势构象中，芳环位于络合平面上，这表明它与金属离子相互作用。当pH高于13时，羧基变为非配位的。然后，二肽是双齿的，最稳定的旋转异构体与无金属配体的相同，即羧基或羰基处于芳环的转位。Pd(II)-Gly-Phe络合物中的甘氨酸络合环在pH 10以下是平面的，当配体变成双齿时，它的平面性发生扭曲。
The conformations of Gly-Phe and Phe-Gly dipeptides and those of their complexes with the Pd(II) ion has been established by means of 1H n.m.r. spectra over various pH ranges. In the most stable rotamer of both dipeptides the bulkiest groups, i.e. carboxylate (or carbonyl) and the aromatic ring, are in trans position to each other. In the 1:1 molar ratio complexes, the dipeptides are the tridentate ligands within the 3–10 pH region. In the predominant conformer the aromatic ring lies over the complex plane, which suggests its interaction with the metal ion. At pH above 13, the carboxyl group becomes non-coordinated. The dipeptides are then bidentate and the most stable rotamers are the same as those found for the metal-free ligands, i.e. the carboxyl or carbonyl group is in the trans position to the aromatic ring. The glycine chelate ring in the Pd(II) Gly-Phe complex is planar up to pH 10 and its distortion from planarity follows when the ligand becomes bidentate.