Application of the Recognizing Ability for L-Cysteine Residue to Peptide-Analysis using the Trigonal-Bipyramidal Palladium(II) Complex

证实了三(2-(二苯基膦)-乙基)膦(PP_3)与五配位的三角-双锥体钯(II)配合物在轴向位置对硫代硫原子的高选择性。为了将这种选择性应用于氨基酸的分离，在含有四种氨基酸L-丙氨酸、L-蛋氨酸、L-青霉胺、L-半胱氨酸的弱碱性水溶液中加入[Pd(Pp_3)(CH_3CN)](BF_4)_2的乙腈溶液，用氯仿提取，氯仿溶液只显示新分离的L-半胱氨酸的核磁共振信号。对L-半胱氨酸和L-蛋氨酸和L-青霉胺的偏好可以用电子和空间位阻的原因来解释。此外，我们还将该选择性应用于谷胱甘肽中L-半胱氨酸残基的检测和还原型谷胱甘肽的测定。PP_3Pd(II)络合物不与氧化形式的谷胱甘肽形成三聚体络合物。这种对氧化态的识别能力对于研究生物氧化还原体系是非常有用的。研究还表明，谷胱甘肽络合物可用于有机锡化合物的鉴别。

The high selectivity for the thiolato sulfur atom in the axial position of the five-coordinate trigonal-bipyramidal palladium(II) complexes with tris (2-(diphenylphosphino) -ethyi)phosphine (pp_3 ) was confirmed. In order to apply such a selectivity to separation of amino acids, an acetonitrile solution of [Pd(pp_3)(CH_3CN)](BF_4)_2 was added to a weakly basic aqueous solution containing four amino acids, L-alanine, L-methionine, L-penicillamine, L-cysteine, and the resultant complex is extracted with chloroform, The chloroform solution showed only the ^<31>P NMR signals for the L-cysteinato complex which was newly isolated. The preference for L-cysteine over L-methionine and L-penicillamine is explained by the electronic and steric reasons. Furthermore, we have applied the selectivity to detection of the L-cysteine residue in glutathione and to determination of the reduced form of glutathione. The pp_3 palladium(II) complex did not react to form a throlato complex with the oxidized form of glutathione. Such a discriminating ability for the oxidation state is quite useful for investigation of the biological redox system. It was also indicated that the glutathionato complex is useful for discrimination of the organotin compounds.