title: Coupling isoelectric focusing gel electrophoresis to mass spectrometry by electrostatic spray ionization.
abstract: Gel electrophoresis has been used for decades as a high-resolution separation technique for proteins and protein isomers but has been limited in the coupling with MS because of low throughput and poor automaticity compared with LC-MS. In this work, we have developed an ambient ionization strategy, electrostatic spray ionization, for in situ ionization of proteins or peptides inside a surfactant-free polyacrylamide gel. The samples can be first separated by isoelectric focusing in a gel and then quickly in situ detected by scanning the gel with the electrostatic spray ionization mass spectrometry. With this strategy, nanograms of proteins or peptides inside a band are enough to be ionized for MS detection. This method for protein/peptide spots visualization is sensitive, providing sample molecular weight information while avoiding spot staining and chemical extraction procedures that can introduce contaminants and sample loss. Proof-of-principle results have demonstrated that the electrostatic spray ionization can produce sample ions from a complex background, and with a spatial resolution matching the isoelectric focusing, it is therefore a good choice to couple directly isoelectric focusing gel electrophoresis with mass spectrometry.
authors.affiliation: Laboratoire d'Electrochimie Physique et Analytique, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Liang
authors.initials: L
authors.lastname: Qiao
authors.forename: Elena
authors.initials: E
authors.lastname: Tobolkina
authors.forename: Baohong
authors.initials: B
authors.lastname: Liu
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Girault
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D007525:Isoelectric Focusing; D008970:Molecular Weight; D010455:Peptides / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D010455:Peptides; D011506:Proteins