title: Disappearance of interfering alkali-metal adducted peaks from matrix-assisted laser desorption/ionization mass spectra of peptides with serine addition to alpha-cyano-4-hydroxycinnamic acid matrix.
abstract: It has been described that ion yield in both positive- and negative-ion matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) of peptides is often inhibited by trace amounts of alkali metals and that the MALDI mass spectra are contaminated by the interfering peaks originating from traces of alkali metals, even when sample preparation is carefully performed. Addition of serine to the commonly used MALDI matrix alpha-cyano-4-hydroxycinnamic acid (CHCA) significantly improved and enhanced the signals of both protonated and deprotonated peptides, [M+H](+) and [M-H](-). The addition of serine to CHCA matrix eliminated the alkali-metal ion adducts, [M+Na](+) and [M+K](+), and the CHCA cluster ions from the mass spectra. Serine and serinephosphate as additives to CHCA enhanced and improved the formation of molecular-related ions of phosphopeptides in negative-ion MALDI mass spectra.
authors: Mass Spectrometry Laboratory, International Graduate School of Arts and Sciences, Yokohama City University, Yokohama 236-0027 Japan.
authors: Takashi
authors: T
authors: Nishikaze
authors: Mitsuo
authors: M
authors: Takayama
mesh_terms: D000818:Animals; D002417:Cattle; D003373:Coumaric Acids / Q000737:chemistry*; D008672:Metals, Alkali / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D010449:Peptide Mapping / Q000379:methods*; D012694:Serine / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods; D013912:Threonine / Q000737:chemistry
chemical_list: D003373:Coumaric Acids; D008672:Metals, Alkali; D010446:Peptide Fragments; C007175:alpha-cyano-4-hydroxycinnamate; D013912:Threonine; D012694:Serine