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Threonine versus isothreonine in synthetic peptides analyzed by high‐resolution liquid chromatography/tandem mass spectrometry
Author(s) -
Kuznetsova Ksenia G.,
Trufanov Pavel V.,
Moysa Alexander A.,
Pyatnitskiy Mikhail A.,
Zgoda Viktor G.,
Gorshkov Mikhail V.,
Moshkovskii Sergei A.
Publication year - 2016
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.7566
Subject(s) - chemistry , orbitrap , threonine , tandem mass spectrometry , chromatography , mass spectrometry , fragmentation (computing) , isobaric labeling , proteome , shotgun proteomics , residue (chemistry) , methionine , amino acid , protein mass spectrometry , proteomics , biochemistry , serine , phosphorylation , computer science , gene , operating system
Rationale One of the problems in proteogenomic research aimed at identification of variant peptides is the presence of peptides with amino acid isomers of different origin in the analyzed samples. Among the most challenging examples are peptides with threonine and isothreonine (homoserine) in their sequences. Indeed, the latter residue may appear in vitro as a methionine substitution during sample preparation for shotgun proteome analysis. Yet, this substitution of Met to isoThr is not encoded genetically and should be unambiguously distinguished from, e.g., point mutations in proteins that result in Met conversion to Thr. Methods In this work we compared tandem mass (MS/MS) spectra produced by an Orbitrap mass spectrometer of Thr‐ and isoThr‐containing tryptic peptides and found a distinctive feature in their collisionally activated fragmentation patterns. Results Up to 84% of MS/MS spectra for peptides containing isoThr residues have been positively specified. We also studied the differences in retention times for peptides containing Thr isoforms that can be further used for their distinction. Conclusions Threonine can be distinguished from isothreonine by its retention time and HCD fragmentation pattern, specifically relative intensity of the b n ‐ product ion, which can be further used in proteomic research. Copyright © 2016 John Wiley & Sons, Ltd.