title: Protein identification platform utilizing micro dispensing technology interfaced to matrix-assisted laser desorption ionization time-of-flight mass spectrometry.
abstract: An integrated protein microcharacterization/identification platform has been developed. The system has been designed to allow a high flexibility in order to tackle challenging analytical problems. The platform comprises a cooled microautosampler, an integrated system for microcolumn HPLC, and a capillary reversed-phase column that is interfaced to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) system via a low internal volume flow-through microdispenser. The chromatographic separation is continuously transferred onto a MALDI target plate as discrete spots as the dispenser ejects bursts of droplets of the column effluent in a precise array pattern. A refrigerated microfraction collector was coupled to the outlet of the flow-through microdispenser enabling enrichment and re-analysis of interesting fractions. The use of target plates pre-coated with matrix simplified and increased the robustness of the system. By including a separation step prior to the MALDI-TOF-MS analysis and hereby minimizing suppression effects allowed us to obtain higher sequence coverage of proteins compared to conventional MALDI sample preparation methodology. Additionally, synthetic peptides corresponding to autophosphorylated forms of the tryptic fragment 485-496 (ALGADDSYYTAR) of tyrosine kinase ZAP-70 were identified at sensitivities reaching 150 amol.
authors.affiliation: Department of Analytical Chemistry, Lund University, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Miliotis
authors.forename: S
authors.initials: S
authors.lastname: Kjellström
authors.forename: P
authors.initials: P
authors.lastname: Onnerfjord
authors.forename: J
authors.initials: J
authors.lastname: Nilsson
authors.forename: T
authors.initials: T
authors.lastname: Laurell
authors.forename: L E
authors.initials: LE
authors.lastname: Edholm
authors.forename: G
authors.initials: G
authors.lastname: Marko-Varga
mesh_terms: D000595:Amino Acid Sequence; D010446:Peptide Fragments / Q000737:chemistry; D010449:Peptide Mapping; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014357:Trypsin / Q000378:metabolism; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D010446:Peptide Fragments; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; D014357:Trypsin