title: Electrospray-assisted laser desorption/ionization and tandem mass spectrometry of peptides and proteins.
abstract: We have constructed an electrospray-assisted laser desorption/ionization (ELDI) source which utilizes a nitrogen laser pulse to desorb intact molecules from matrix-containing sample solution droplets, followed by electrospray ionization (ESI) post-ionization. The ELDI source is coupled to a quadrupole ion trap mass spectrometer and allows sampling under ambient conditions. Preliminary data showed that ELDI produces ESI-like multiply charged peptides and proteins up to 29 kDa carbonic anhydrase and 66 kDa bovine albumin from single-protein solutions, as well as from complex digest mixtures. The generated multiply charged polypeptides enable efficient tandem mass spectrometric (MS/MS)-based peptide sequencing. ELDI-MS/MS of protein digests and small intact proteins was performed both by collisionally activated dissociation (CAD) and by nozzle-skimmer dissociation (NSD). ELDI-MS/MS may be a useful tool for protein sequencing analysis and top-down proteomics study, and may complement matrix-assisted laser desorption/ionization (MALDI)-based measurements.
authors.affiliation: Department of Chemistry and Biochemistry, University of California-Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Ivory X
authors.initials: IX
authors.lastname: Peng
authors.forename: Jentaie
authors.initials: J
authors.lastname: Shiea
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Ogorzalek Loo
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Loo
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D010449:Peptide Mapping / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020539:Sequence Analysis, Protein / Q000379:methods*; D013048:Specimen Handling / Q000295:instrumentation* / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization / Q000295:instrumentation* / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods; D014159:Transducers