MALDI MS/MS study of As(III) complexes with glutathione, glutathione disulphide and other ligands

Abstract

Abstract The formation of complexes between As(III) and two redox couples GSH/GSSG, Cys/Cyst, and Cyt c, was evaluated by MALDI MS and MS/MS. Structural elucidation of complexes is reported, and the redox properties are discussed. Particular attention was addressed to the gas-phase ion chemistry of high molecular weight species (i.e., [As(GSH)4]+). The formation of the oxidized ligand from complexes where a thiol free group is present, gives evidence on an intramolecular redox process initiated by a laser induced oxidation step. MS/MS experiments also demonstrated that GSSG, Cyst and Cyt c act as bidentate ligands, determining the formation of cyclic structures.