Threonine versus isothreonine in synthetic peptides analyzed by high-resolution liquid chromatography/tandem mass spectrometry

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...

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Bibliographic Details
Published in:Rapid communications in mass spectrometry 2016-06, Vol.30 (11), p.1323-1331
Main Authors: Kuznetsova, Ksenia G., Trufanov, Pavel V., Moysa, Alexander A., Pyatnitskiy, Mikhail A., Zgoda, Viktor G., Gorshkov, Mikhail V., Moshkovskii, Sergei A.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Biomedical materials
Chromatography, High Pressure Liquid - methods
Fragmentation
Humans
Isomerism
Liquid chromatography
Mass spectrometry
Peptides
Peptides - chemistry
Residues
Spectra
Surgical implants
Tandem Mass Spectrometry - methods
Threonine - analysis
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Summary: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 bn‐ product ion, which can be further used in proteomic research. Copyright © 2016 John Wiley & Sons, Ltd.
ISSN:0951-4198
1097-0231
DOI:10.1002/rcm.7566