Isotope-Edited Amide II Mode: A New Label for Site-Specific Vibrational Spectroscopy

Esther S. Brielle*, Isaiah T. Arkin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Vibrational spectroscopy is a powerful tool used to analyze biological and chemical samples. However, in proteins, the most predominant peaks that arise from the backbone amide groups overlap one another, hampering site-specific analyses. Isotope editing has provided a robust, noninvasive approach to overcome this hurdle. In particular, the 1-13C═16O and 1-13C═18O labels that shift the amide I vibrational mode have enabled 1D- and 2D-IR spectroscopy to characterize proteins with excellent site-specific resolution. Herein, we expand the vibrational spectroscopy toolkit appreciably by introducing the 1-13C15N probe at specific locations along the protein backbone. A new, isotopically edited amide II peak is observed clearly in the spectra despite the presence of unlabeled modes arising from the rest of the protein. The experimentally determined shift of −30 cm-1is reproduced by DFT calculations providing further credence to the mode assignment. Since the amide II mode arises from different elements than the amide I mode, it affords molecular insights that are both distinct and complementary. Moreover, multiple labeling schemes may be used simultaneously, enhancing vibrational spectroscopy’s ability to provide detailed molecular insights.

Original languageAmerican English
Pages (from-to)6634-6638
Number of pages5
JournalJournal of Physical Chemistry Letters
Issue number28
StatePublished - 22 Jul 2021

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© 2021 American Chemical Society


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