title: Improved procedures for N-terminal sulfonation of peptides for matrix-assisted laser desorption/ionization post-source decay peptide sequencing.
abstract: Post source decay (PSD) analysis of precursor ions generated from matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a powerful tool for amino acid sequencing and primary structure analysis of proteins. N-Terminal sulfonation has become an effective derivatization strategy in facilitating de novo peptide sequencing by the formation of predominate y-type ion series in MALDI PSD spectra. Recently, an effective and inexpensive N-terminal derivatization method has been reported using 4-sulfophenyl isothiocyanate (SPITC) as the derivatization reagent (J. Mass. Spectrom. 2003; 38: 373-377). In this paper, we report an improvement in the derivatization procedure with this reagent that involves replacing an organic co-reagent with other chemicals and eliminating the use of organic solvent. The method is demonstrated on a model peptide and on tryptic digests of two proteins. The results indicate that the improved sulfonation reaction can be implemented with high efficiency under aqueous conditions and that the sensitivity of mass detection can be increased considerably.
authors.affiliation: Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Dongxia
authors.initials: D
authors.lastname: Wang
authors.forename: Suzanne R
authors.initials: SR
authors.lastname: Kalb
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Cotter
mesh_terms: D000085:Acetates / Q000737:chemistry*; D000595:Amino Acid Sequence; D005021:Ethylamines / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry; D017879:Isothiocyanates / Q000737:chemistry*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry; D010047:Ovalbumin / Q000737:chemistry; D010455:Peptides / Q000032:analysis* / Q000737:chemistry*; D011487:Protein Conformation; D011786:Quality Control; D015203:Reproducibility of Results; D012492:Salts / Q000737:chemistry; D012680:Sensitivity and Specificity; D020539:Sequence Analysis, Protein / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013450:Sulfones / Q000737:chemistry*
chemical_list: D000085:Acetates; D005021:Ethylamines; D007202:Indicators and Reagents; D017879:Isothiocyanates; D009842:Oligopeptides; D010455:Peptides; D012492:Salts; C040475:Src peptide; D013450:Sulfones; D010047:Ovalbumin; C018824:ammonium acetate; C016162:triethylamine