title: Characterization of chemical modification of tryptophan by matrix-assisted laser desorption/ionization mass spectrometry.
abstract: Tert- butylation of tryptophan (2', 5', 7'- tri tertiary butyl tryptophan), formed during acidolytic cleavage of synthetic peptides Ac-KLVYWAE-CONH(2) (A-YW) and Ac-KLVWWAE-CONH(2) (A-WW), that are analogs of the fragment of Alzheimer's beta-amyloid peptide Ac-KLVFFAE-CONH(2), during solid-phase peptide synthesis, was characterized by matrix-assisted laser desorption/ionization time of flight/time of flight (MALDI TOF/TOF) mass spectrometry. Crude peptide was fractionated by high performance liquid chromatography. Peptide fractions were sequenced and modified tryptophan was determined with the help of MALDI TOF/TOF mass spectra. Thus, it is possible to pinpoint the particular tryptophan residue that undergoes modification during synthesis of peptides containing multiple tryptophan residues.
authors.affiliation: Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad-500 007, India.
authors.forename: C Sivakama
authors.initials: CS
authors.lastname: Sundari
authors.forename: K
authors.initials: K
authors.lastname: Chakraborty
authors.forename: R
authors.initials: R
authors.lastname: Nagaraj
authors.forename: M V
authors.initials: MV
authors.lastname: Jagannadham
mesh_terms: D000595:Amino Acid Sequence; D024322:Amino Acids, Aromatic / Q000737:chemistry; D016229:Amyloid beta-Peptides / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry
chemical_list: C018683:2,5,7-tri-tert-butyltryptophan; D024322:Amino Acids, Aromatic; D016229:Amyloid beta-Peptides; D009842:Oligopeptides; D010446:Peptide Fragments; D014364:Tryptophan