Characterization of chemical modification of tryptophan by matrix-assisted laser desorption/ionization mass spectrometry

Tert-butylation of tryptophan (2′,5′,7′-tri tertiary butyl tryptophan),formed during acidolytic cleavage of synthetic peptides ac-klvywae-conh2 (a-yw) and ac-klvwwae-conh2 (a-ww),that are analogs of the fragment of alzheimer's β-amyloid peptide ac-klvffae-conh2,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. © 2010 bentham science publishers ltd.