Structural and NMR investigations of the ternary adducts of twenty α-amino acids and selected dipeptides with a chiral, diaqua-ytterbium complex
Structural and NMR investigations of the ternary adducts of twenty α-amino acids and selected dipeptides with a chiral, diaqua-ytterbium complex
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DOI：
10.1039/b311791j
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发表时间：
2004-01-01
影响因子：
4
通讯作者：
Salamano, S
中科院分区：
文献类型：
--
作者：
Dickins, RS;Batsanov, AS;Salamano, S
已进行了详细的调查的性质的结合的20个常见的α-氨基酸和各种选定的二肽的手性，二水合镱复合物在水溶液中。偶极H-1 NMR顺磁位移的分析表明，α-氨基酸形成一个共同的螯合结构内的九个坐标的单帽正方形反棱柱配位环境，与胺N轴向设置。九螯合YbL 1-氨基酸加合物（甘氨酸，丙氨酸，丝氨酸，苏氨酸，蛋氨酸）的晶体结构证实了这一点。与二肽（例如Gly-Ala、Gly-Ser、Gly-Met、Gly-Asp、Gly-Asn、Gly-His、Ser-Met、Asp-Phe、His-Gly）的三元复合物也有利于末端胺作为轴向供体，与邻近的酰胺基团结合以产生五环螯合物。只有在N-末端天冬氨酸的情况下，才发现通过侧链功能螯合的证据。镱离子与氨基酸结合时的手性环境也用近红外圆二色光谱进行了研究。
A detailed investigation of the nature of the binding of each of the 20 common alpha-amino acids and various selected dipeptides to a chiral, diaqua-ytterbium complex in aqueous solution has been carried out. Analysis of the dipolar H-1 NMR paramagnetic shifts suggests that the alpha-amino acids form a common chelated structure within a nine-coordinate mono-capped square antiprismatic coordination environment, with the amine N axially disposed. Crystal structures of nine chelated YbL1-amino acid adducts (Gly, Ala, Ser, Thr, Met) confirm this. The ternary complexes with dipeptides (e.g. Gly-Ala, Gly-Ser, Gly-Met, Gly-Asp, Gly-Asn, Gly-His, Ser-Met, Asp-Phe, His-Gly) also favour the terminal amine as the axial donor with the proximate amide group binding to generate a five-ring chelate. Evidence for chelation through side-chain functionality was found only in the case of N-terminal Asp. The chiral environment about the ytterbium ion upon amino acid binding has also been probed using near-IR circular dichroism spectroscopy.