title: Characteristic pH and electrolyte concentration dependences of 2-aminopyridine-derivatized oligosaccharides (N-glycans) in sonic-spray ionization mass spectrometry.
abstract: The intensities of ion signals from neutral oligosaccharides (N-glycans) derivatized with 2-aminopyridine (PA) were analyzed by ion trap mass spectrometry with a sonic-spray ionization (SSI) source, in both positive- and negative-ion modes, while varying the pH and concentration of ammonium acetate buffer solution. Two characteristic results are reported and discussed. The first characteristic is the pH dependence of the ion intensities; on increasing the solution pH from 4.3 to 8.6, positive ion intensities increase and negative ion intensities decrease. The second characteristic concerns the dependence of ion intensities on electrolyte concentration; on increasing the electrolyte concentration, the SSI efficiency for the PA N-glycans first increases and then decreases. Assuming that the SSI mechanism essentially conforms to the statistical charging model and the charge residue model, a new model that focuses a great deal of attention on the counter (electrolyte) ion distribution surrounding the solvated analyte (PA N-glycan) is proposed, in particular to rationalize the characteristic pH dependence.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 001-0021, Japan. deguchi@glyco.sci.hokudai.ac.jp
authors.forename: Kisaburo
authors.initials: K
authors.lastname: Deguchi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takegawa
authors.forename: Atsumu
authors.initials: A
authors.lastname: Hirabayashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Nishimura
mesh_terms: D000631:Aminopyridines / Q000737:chemistry*; D000818:Animals; D002853:Chromatography, Liquid; D004573:Electrolytes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007477:Ions; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D011134:Polysaccharides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000631:Aminopyridines; D004573:Electrolytes; D007477:Ions; D011134:Polysaccharides; C032439:alpha-aminopyridine