title: Generation of mass tags by the inherent electrochemistry of electrospray for protein mass spectrometry.
abstract: We present herein a review of our work on the on-line electrochemical generation of mass tags toward cysteine residues in peptides and proteins. Taking advantage of the inherent electrochemical nature of electrospray generated from a microfabricated microspray emitter, selective probes for cysteine were developed and tested for on-line nonquantitative mass tagging of peptides and proteins. The nonquantitative aspect of the covalent tagging thus allows direct counting of free cysteines in the mass spectrum of a biomolecule through additional adduct peaks. Several substituted hydroquinones were investigated in terms of electrochemical properties, and their usefulness for on-line mass tagging during microspray experiments were assessed with L-cysteine, peptides, and intact proteins. Complementarily, numerical simulations were performed to properly understand the respective roles of mass transport, kinetics of electrochemical-chemical reactions, and design of the microspray emitter in the mass tagging overall efficiency. Finally, the on-line electrochemical tagging of cysteine residues was applied to the analysis of tryptic peptides of purified model proteins for protein identification through peptide mass fingerprinting.
authors.affiliation: Laboratoire d'Electrochimie Physique et Analytique, Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Christophe
authors.initials: C
authors.lastname: Roussel
authors.forename: Loïc
authors.initials: L
authors.lastname: Dayon
authors.forename: Niels
authors.initials: N
authors.lastname: Lion
authors.forename: Tatiana C
authors.initials: TC
authors.lastname: Rohner
authors.forename: Jacques
authors.initials: J
authors.lastname: Josserand
authors.forename: Joël S
authors.initials: JS
authors.lastname: Rossier
authors.forename: Henrik
authors.initials: H
authors.lastname: Jensen
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Girault
mesh_terms: D003545:Cysteine / Q000032:analysis*; D004563:Electrochemistry; D008832:Microchemistry / Q000379:methods*; D010455:Peptides / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation / Q000379:methods
chemical_list: D010455:Peptides; D011506:Proteins; D003545:Cysteine