Insights into the Molecular Mechanisms of Protein Platination from a Case Study: The Reaction of Anticancer Platinum(II) Iminoethers with Horse Heart Cytochrome c

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• 作者：Angela Casini ; Chiara Gabbiani ; Guido Mastrobuoni ; Raffaella Zoe Pellicani ; Francesco Paolo Intini ; Fabio Arnesano ; Giovanni Natile ; Gloriano Moneti ; Simona Francese ; Luigi Messori
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：October 30, 2007
• 年：2007
• 卷：46
• 期：43
• 页码：12220 - 12230
• 全文大小：212K
• 年卷期：v.46,no.43(October 30, 2007)
• ISSN：1520-4995

文摘

The interactions of anticancer metallodrugs with proteins are attracting a growing interest inthe current literature because of their relevant pharmacological and toxicological consequences. Tounderstand in more depth the nature of those interactions, we have investigated the reactions of fouranticancer platinum(II) iminoether complexes, namely, trans- and cis-EE (trans- and cis-[PtCl₂{(E)-HN=C(OCH₃)CH₃}₂], respectively) and trans- and cis-Z (trans- and cis-[PtCl₂(NH₃){(Z)-HN=C(OCH₃)CH₃}],respectively), with horse heart cytochrome c (cyt c). Our investigation was performed using mainlyelectrospray ionization mass spectrometry (ESI MS) but was also supported by NMR, inductively coupledplasma optical emission spectroscopy (ICP OES), and absorption electronic spectroscopy. ESI MS spectraclearly revealed the formation of a variety of platinum-protein adducts predominantly corresponding tomonoplatinated cyt c species. From a careful analysis of the major ESI MS peaks, specific informationon the nature of the protein-bound metallic fragments and on the underlying metallodrug-cyt c reactionswas gained for the various cases. We found that trans-EE produces a major cyt c adduct (12 667 Da) thatis different from that produced by either cis-EE or by trans-Z and cis-Z (12 626 Da). In particular, occurrenceof extensive hydrolysis/aminolysis (the latter fostered by ammonium carbonate buffer) of the iminoetherligands and formation of the corresponding amides/amidines has been unambiguously documented. Thereactivity of the iminoether ligands is greatly enhanced by the presence of cyt c as inferred from comparativeNMR solution studies. Additional ESI MS measurements recorded on enzymatically cleaved samples ofplatinated cyt c adducts, together with NMR investigation of the cyt c/trans-EE adduct, strongly suggestthat protein platination primarily occurs at Met 65. The biological and pharmacological implications ofthe described protein platination processes are discussed.