Dissociation reactions of gaseous ferro-, ferri-, and apo-cytochrome c ions
Electrochemical reduction of the iron bound in the heme group of cytochrome c is shown to occur in the nano-electrospray capillary if the protein is sprayed from neutral water using a steel wire as the electrical contact. Quadrupole ion trap collisional activation is used to study the dissociation reactions of cytochrome c as a function of the oxidation state of the iron. Oxidized (Fe(III)) cytochrome c dissociates via sequence-specific amide bond cleavage, while the reduced (Fe(II)) form of the protein dissociates almost exclusively by loss of protonated heme. Apo-cytochrome c, from which the heme has been removed either via gas-phase dissociation of the reduced holo-protein or via solution chemistry, dissociates via amide bond cleavage in similar fashion to the oxidized holo-protein.
Unable to display preview. Download preview PDF.
- 13.Falk, J. E. Porphyrins and Metalloporphyrins: Their General, Physical, and Coordination Chemistry, and Laboratory Methods; Elsevier Publishing Company: New York, 1964.Google Scholar
- 20.Reid, G. E.; Wu, J.; Chrisman, P. A.; Wells, J. M.; McLuckey, S. A. Charge State Dependent Sequence Analysis of Protonated Ubiquitin Ions via Ion Trap Tandem Mass Spectrometry. Anal. Chem. 2001, in press.Google Scholar
- 21.Newton, K. A.; Chrisman, P. A.; Reid, G. E.; Wells, J. M.; McLuckey, S. A. Gaseous Apomyoglobin Ion Dissociation in a Quadrupole Ion Trap: (M+2H)2+ − (M+21H)21+. Int. J. Mass Spectrom. 2001, in press.Google Scholar