Site-specific Localization of D-Amino Acids in Bioactive Peptides by Ion Mobility Spectrometry
In this study, we describe a site-specific strategy to rapidly and precisely localize D-amino acids in peptides by ion mobility spectrometry (IMS) analysis of mass spectrometry (MS)-generated epimeric fragment ions. Briefly, the D/L-peptide epimers are separated by online reversed-phase liquid chromatography (LC) and fragmented by collision induced dissociation (CID), followed by IMS analysis. The epimeric fragment ions resulting from D/L-peptide epimers exhibit arrival time differences, thus showing different mobility in IMS. The arrival time shift between the epimeric fragment ions is used as criteria to localize the D-amino acid substitution. We provide the technical details on sample preparation, LC-tandem mass spectrometry analysis, data processing, and collisional cross-section calibration.
KeywordsNeuropeptide Peptidomics De novo sequencing Mass spectrometry Crustacean Ion mobility
This work is supported in part by the National Institutes of Health (NIH) grant (R01DK071801 to LL) and the National Science Foundation grant (CHE-1413596 to LL). LL acknowledges an H. I. Romnes Faculty Research Fellowship from UW-Madison, Tianjin 1000 Talent Plan from Tianjin China and Changjiang Professorship from the Chinese Ministry of Education. C.L. acknowledges an NIH-supported Chemistry Biology Interface Training Program Predoctoral Fellowship (grant number T32-GM008505) and an NSF Graduate Research Fellowship (DGE-1256259). We are grateful to Prof. Jonathan V. Sweedler, Dr. Lu Bai, and Itamar Livnat (UIUC) for helpful discussions and insightful suggestions on this project.
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