Mass spectrometry based strategy for studies of binding sites and structural changes of cisplatin binding to myoglobin.

Abstract

It is of great significance to investigate the interaction of the metallodrug cisplatin (cis-[PtCl2 (NH3 )2 ]) with myoglobin for understanding of the mechanism of action of cisplatin and the overexpression of myoglobin in tumor cells. The reactions of cisplatin and myoglobin were incubated under different conditions. A mass spectrometry (MS)-based strategy combining full proteolysis and limited proteolysis was developed for comprehensive studies of cisplatin-myoglobin interaction. The binding sites of cisplatin on myoglobin were identified as Trp14, His64, His81, His113 and His116 using electrospray ionization multiple-stage tandem mass spectrometry (ESI-MSn ) without liquid chromatography (LC) separation. The relative abundances of digested peptides from platinated myoglobin were obviously higher than those from native samples by limited proteolysis. An alternative and simple approach was developed to successfully monitor conformational changes of myoglobin induced by cisplatin binding using an ESI-MS-based quantification method combined with limited proteolysis. Meanwhile, His64 was firstly found to coordinate to platinum, which was likely to affect hydrogen bonds with the oxygen in the heme group. Copyright © 2016 John Wiley & Sons, Ltd.