title: A convenient purification and preconcentration of peptides with alpha-cyano-4-hydroxycinnamic acid matrix crystals in a pipette tip for matrix-assisted laser desorption/ionization mass spectrometry.
abstract: Peptide samples derived from enzymatic in-gel digestion of proteins resolved by gel electrophoresis often contain high amount of salts originating from reaction and separation buffers. Different methods are used for desalting prior to matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), e.g. reversed-phase pipette tip purification, on-target washing, adding co-matrices, etc. As a suitable matrix for MALDI MS of peptides, alpha-cyano-4-hydroxycinnamic acid (CHCA) is frequently used. Crystalline CHCA shows the ability to bind peptides on its surface and because it is almost insoluble in acidic water solutions, the on-target washing of peptide samples can significantly improve MALDI MS signals. Although the common on-target washing represents a simple, cheap and fast procedure, only a small portion of the available peptide solution is efficiently used for the subsequent MS analysis. The present approach is a combination of the on-target washing principle carried out in a narrow-end pipette tip (e.g. GELoader tip) and preconcentration of peptides from acidified solution by passing it through small CHCA crystals captured inside the tip on a glass microfiber frit. The results of MALDI MS analysis using CHCA-tip peptide preconcentration are comparable with the use of homemade POROS R2 pipette tip microcolumns. Advantages and limitations of this approach are discussed.
authors.affiliation: Faculty of Military Health Sciences, Institute of Molecular Pathology, University of Defence, Trebesská 1575, CZ-50001 Hradec Králové, Czech Republic.
authors.forename: Helena
authors.initials: H
authors.lastname: Rehulková
authors.forename: Jana
authors.initials: J
authors.lastname: Chalupová
authors.forename: Marek
authors.initials: M
authors.lastname: Sebela
authors.forename: Pavel
authors.initials: P
authors.lastname: Rehulka
mesh_terms: D005591:Chemical Fractionation / Q000379:methods*; D003373:Coumaric Acids / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification; D012492:Salts / Q000737:chemistry / Q000302:isolation & purification; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D003373:Coumaric Acids; D010455:Peptides; D012492:Salts; C007175:alpha-cyano-4-hydroxycinnamate