ac501200h_si_001.pdf (1.17 MB)
Discrimination of Leucine and Isoleucine in Peptides Sequencing with Orbitrap Fusion Mass Spectrometer
journal contribution
posted on 2014-07-15, 00:00 authored by Albert T. Lebedev, Eugen Damoc, Alexander
A. Makarov, Tatiana Yu. SamginaAn
efficient approach to easy and reliable differentiation between
isomeric leucine and isoleucine in peptide sequencing utilizes multistage
electron transfer dissociation and higher energy collision activated
dissociation in the Orbitrap Fusion mass spectrometer. The MS3 method involves production and isolation of primary odd-electron
z• ions, followed by radical site initiation of
their fragmentation with formation of w-ions, characteristic of the
isomeric amino acid residues. Six natural nontryptic peptides isolated
from the secretion of frog Rana ridibunda were studied.
Their lengths were in the range between 15 and 37 amino acids and
the number of targeted isomeric (Leu/Ile) residues varied between
1 and 7. The experiments were successful in all 22 cases of Leu/Ile
residues, leaving no doubts in identification. The method is extremely
selective as the targeted w-ions appear to be the most intense in
the spectra. The proposed approach may be incorporated into shotgun
proteomics algorithms and allows for the development of an exclusively
mass spectrometric method for automated complete de novo sequencing of various peptides and proteins.