Feketeová Linda, Ryzhov Victor, O'Hair Richard A J
School of Chemistry, University of Melbourne, Victoria 3010, Australia.
Rapid Commun Mass Spectrom. 2009 Oct;23(19):3133-43. doi: 10.1002/rcm.4234.
Incubation of the histidine-containing peptides (GH, HG, GGH, GHG, HGG) and methionine-containing peptides (GM, MG, GGM, GMG, MGG) with the platinum complexes Pt(terpy)Cl (A) and Pt(dien)Cl (B) followed by electrospray ionisation (ESI) led to a number of singly and doubly charged ternary platinum peptide complexes, including Pt(L)M and Pt(L)M-H (where L = the ligand terpy or dien; M is a peptide). Each of the Pt(L)M complexes was subjected to electron capture dissociation (ECD), collision-induced dissociation (CID) and electron-induced dissociation (EID), while each of the Pt(L)M-H complexes was subjected to CID and EID. Results from ECD suggest that the free electron is captured by the metal ion thus weakening the bonds to its ligands. In the case of the ligand terpy, which binds more strongly than dien, this weakening leads to the loss of the peptide. The minor products in the ECD spectra of Pt(terpy)M complexes do show fragmentation along the peptide backbone, but the ions observed are of the a-, b-, and y-type. For the complexes with methionine-containing peptides, a marker ion, Pt(L)SCH(3), was found which is indicative of binding of Pt to the methionine side chain. For the histidine-containing peptides, an ion containing platinum, the auxiliary ligand, and the histidine imine was observed in many instances, thus indicating the binding of the histidine side chain to the metal, but other modes of Pt coordination (N-terminus) were also found to be competitive. These findings are consistent with a recent finding (Sze et al. J. Biol. Inorg. Chem. 2009; 14: 163) that Pt occupies the methionine-rich copper(I)-binding site rather than histidine-rich copper(II)-binding site in the CopC protein.
将含组氨酸的肽（GH、HG、GGH、GHG、HGG）和含甲硫氨酸的肽（GM、MG、GGM、GMG、MGG）与铂配合物Pt(terpy)Cl（A）和Pt(dien)Cl（B）进行孵育，随后进行电喷雾电离（ESI），得到了许多单电荷和双电荷的三元铂肽配合物，包括Pt(L)M和Pt(L)M-H（其中L = 配体terpy或dien；M为肽）。对每个Pt(L)M配合物进行了电子捕获解离（ECD）、碰撞诱导解离（CID）和电子诱导解离（EID），而对每个Pt(L)M-H配合物进行了CID和EID。ECD结果表明，自由电子被金属离子捕获，从而削弱了与配体的键。在配体terpy比dien结合更强的情况下，这种削弱导致肽的丢失。Pt(terpy)M配合物的ECD谱中的次要产物确实显示出沿肽主链的碎片化，但观察到的离子为a-、b-和y型。对于含甲硫氨酸肽的配合物，发现了一个标记离子Pt(L)SCH(3)，它表明Pt与甲硫氨酸侧链的结合。对于含组氨酸的肽，在许多情况下观察到一个含有铂、辅助配体和组氨酸亚胺的离子，从而表明组氨酸侧链与金属的结合，但也发现其他Pt配位模式（N端）具有竞争性。这些发现与最近的一项发现（Sze等人，《生物无机化学杂志》，2009年；14: 163）一致，即在CopC蛋白中，Pt占据富含甲硫氨酸的铜（I）结合位点而非富含组氨酸的铜（II）结合位点。
