title: Intact and top-down characterization of biomolecules and direct analysis using infrared matrix-assisted laser desorption electrospray ionization coupled to FT-ICR mass spectrometry.
abstract: We report the implementation of an infrared laser onto our previously reported matrix-assisted laser desorption electrospray ionization (MALDESI) source with ESI post-ionization yielding multiply charged peptides and proteins. Infrared (IR)-MALDESI is demonstrated for atmospheric pressure desorption and ionization of biological molecules ranging in molecular weight from 1.2 to 17 kDa. High resolving power, high mass accuracy single-acquisition Fourier transform ion cyclotron resonance (FT-ICR) mass spectra were generated from liquid- and solid-state peptide and protein samples by desorption with an infrared laser (2.94 mum) followed by ESI post-ionization. Intact and top-down analysis of equine myoglobin (17 kDa) desorbed from the solid state with ESI post-ionization demonstrates the sequencing capabilities using IR-MALDESI coupled to FT-ICR mass spectrometry. Carbohydrates and lipids were detected through direct analysis of milk and egg yolk using both UV- and IR-MALDESI with minimal sample preparation. Three of the four classes of biological macromolecules (proteins, carbohydrates, and lipids) have been ionized and detected using MALDESI with minimal sample preparation. Sequencing of O-linked glycans, cleaved from mucin using reductive beta-elimination chemistry, is also demonstrated.
authors.affiliation: W.M. Keck FT-ICR Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Sampson
authors.forename: Kermit K
authors.initials: KK
authors.lastname: Murray
authors.forename: David C
authors.initials: DC
authors.lastname: Muddiman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002241:Carbohydrates / Q000737:chemistry*; D002417:Cattle; D002645:Chickens; D004530:Egg Yolk / Q000737:chemistry; D006736:Horses; D008055:Lipids / Q000737:chemistry*; D008892:Milk / Q000737:chemistry; D008969:Molecular Sequence Data; D009077:Mucins / Q000737:chemistry / Q000378:metabolism; D009211:Myoglobin / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D011506:Proteins / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D002241:Carbohydrates; D008055:Lipids; D009077:Mucins; D009211:Myoglobin; D011134:Polysaccharides; D011506:Proteins