Enhancing the intensities of lysine-terminated tryptic peptide ions in matrix-assisted laser desorption/ionization mass spectrometry

Abstract
Tryptic digests of three proteins are reacted with O‐methylisourea in order to convert lysine residues to homoarginines. The resulting homoarginine‐terminated peptides exhibit more intense MALDI mass spectral peaks than their lysine‐terminated predecessors. This simple chemical reaction should therefore facilitate protein sequencing and mass mapping. Copyright © 2000 John Wiley & Sons, Ltd.