Determination of binding sites in carboplatin-bound cytochrome c using electrospray ionization mass spectrometry and tandem mass spectrometry

✍ Scribed by Gaosheng Yang; Ren Miao; Chen Jin; Yuhua Mei; Huiwei Tang; Jin Hong; Zijian Guo; Longgen Zhu

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 213 KB
• Volume: 40
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.875

✦ Synopsis

Abstract

Interaction of carboplatin with cytochrome c (Cyt. c) has been investigated by electrospray ionization mass spectrometry (ESI‐MS) and tandem mass spectrometry (MS/MS). ESI‐MS studies revealed that the ring‐opened adducts of carboplatin with Cyt. c were formed in the stoichiometric ratio of 1 : 1 and 2 : 1 at pH 5.0 and 37 °C and in the stoichiometric ratio of 1 : 1 only at pH 7.0 and 37 °C. It was also found that Cyt. c could be cleaved by carboplatin at pH 2.5 and 50 °C. The cleaved fragments of Cyt. c were determined by ESI‐MS and MS/MS analysis to be Glu66∼Met80, Ac‐Gly01∼Met65, Glu66∼Glu104, Ac‐Gly01∼Met80 and Ile81∼Glu104. The carboplatin prefers to anchor to Met65 first, then to Met80. To further confirm the binding site of Met, AcMet‐Gly was used as the model molecule to investigate its interaction with carboplatin and its hydrolysis reaction. On the basis of species detected during the reaction monitored by ESI‐MS, a possible pathway of the cleavage reaction was proposed. Copyright © 2005 John Wiley & Sons, Ltd.