Faculty Publications

Title

Cysteine-linked aromatic nitriles as UV resonance Raman probes of protein structure

Document Type

Article

Keywords

Cyanophenylalanine, Peptides, Proteins, Unnatural amino acids, UV resonance Raman

Journal/Book/Conference Title

Journal of Raman Spectroscopy

Volume

43

Issue

9

First Page

1244

Last Page

1249

Abstract

Nitriles introduced into peptides and proteins can serve as useful vibrational spectroscopic probes, because the nitrile C≡N stretch is well isolated from backbone and sidechain vibrational bands. Aromatic nitriles offer large nC≡N absorption intensity in infrared spectra and resonance enhancement in Raman spectra with ultraviolet excitation. We report the ultraviolet resonance Raman spectra of cyanophenylalanine attached to cysteine, through linkage reactions that are applicable to cysteine residues in proteins. Excitation profiles are reported, and the nC≡N detection limit is estimated to be 5μM. The band position is sensitive to solvent polarity and especially to strong H-bonding. The derivatization of mastoparan X peptide at introduced cysteine residues demonstrated the effectiveness of a cyanophenylcysteine probe in reporting the lowered environmental polarity when the peptide was incorporated into liposomes. For an asymmetrical cyanophenyl derivative, 2-CBCys, the intensity ratio of asymmetric and symmetric ring modes, n8 b and n8 a, was found to respond to solvent polarity and not to H-bonding. ©2012 John Wiley & Sons, Ltd.

Original Publication Date

9-1-2012

DOI of published version

10.1002/jrs.3167

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