A method for N-terminal de novo sequence analysis of proteins by matrix-assisted laser desorption/ionization mass spectrometry

A novel method for isolation and de novo sequencing of N-terminal peptides from proteins is described. The method presented here combines selective chemical tagging using succinimidyloxycarbonylmethyl tris(2,4,6-trimethoxyphenyl)phosphonium bromide (TMPP-Ac-OSu) at the N-alpha-amino group of peptides after digestion by metalloendopeptidase (from Grfola frondosa) and selective capture procedures using p-phenylenediisothiocyanate resin, by which the IN-terminal peptide can be isolated, whether or not it is N-terminally blocked. The isolated N-terminal peptide modified N-terminally with TMPP--Ac-OSu reagent produces a simple fragmentation pattern under tandem mass spectrometric analysis to significantly facilitate sequencing. (c) 2008 Elsevier Inc. All rights reserved.