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Top-down mass spectrometric approach for the full characterization of insulin--cisplatin adducts

Authors :
Moreno-Gordaliza, Estefania
Canas, Benito
Palacios, Maria A.
Gomez-Gomez, M. Milagros
Source :
Analytical Chemistry. May 1, 2009, Vol. 81 Issue 9, p3507, 10 p.
Publication Year :
2009

Abstract

The interaction of the antitumor drug cisplatin with insulin was studied using a top-down mass spectrometric approach. In vitro incubations were prepared under acidic and physiological conditions at different insulin/cisplatin molar ratios for different incubation times. Size exclusion chromatography--inductively coupled plasma mass spectrometry (SEC--ICPMS) analysis enabled the specific detection of platinum containing species attributed to the binding of the drug to the protein. Further analysis through matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and nanoelectrospray ionization mass spectrometry using a linear ion trap (nESI-LIT-MS) allowed the identification of platinated mono-, di-, and even triadducts in the incubations. Platinum binding sites were identified by [CID-MS.sup.n] as B chain N-terminus, His5, and probably His10 residues, which turned out to be the same, regardless of the incubation conditions. Evidence on the binding of Pt to B chain Cys7 was also observed. Working with the LIT zoom scan mode provides enough resolution to discern the isotopic pattern for both precursor and fragment ions, allowing the differentiation of platinum-containing ions. The elucidation of platinum binding sites in a native protein through a top-down approach has been performed for the first time with this type of instrument.

Details

Language :
English
ISSN :
00032700
Volume :
81
Issue :
9
Database :
Gale General OneFile
Journal :
Analytical Chemistry
Publication Type :
Academic Journal
Accession number :
edsgcl.199684514