An EThcD-based method for discrimination of leucine and isoleucine residues in tryptic peptidesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 21 августа 2017 г.
Аннотация:An EThcD-based approach for the reliable discrimination of isomeric leucine and
isoleucine residues in peptide de novo sequencing procedure has been proposed. A
multistage fragmentation of peptide ions was performed with Orbitrap Elite mass
spectrometer in electrospray ionization mode. At the first stage, z-ions were produced
by ETD or ETcaD fragmentation of doubly or triply charged peptide precursor ions.
These primary ions were further fragmented by HCD with broad-band ion isolation, and
the resulting w-ions showed different mass for leucine and isoleucine residues. The
procedure did not require manual isolation of specific z-ions prior to HCD stage. 43
tryptic peptides (3 to 27 residues) obtained by trypsinolysis of human serum albumin
(HSA) and gp188 protein were analyzed. To demonstrate a proper solution for radical
site migration problem three non-tryptic peptides were also analyzed. A total of 93
leucine and isoleucine residues have been considered and 83 of them were correctly
identified. The developed approach can be a reasonable substitution for additional
Edman degradation procedure which is still used in peptide sequencing for leucine and
isoleucine discrimination.