article · 05/08/2024
Relationships between conformational and vibrational features of tryptophan characteristic Raman markers
Résumé
Tryptophan (Trp) residue provides characteristic vibrational markers to the middle wavenumber spectral region of the Raman spectra recorded from peptides and proteins. In this report, we were particularly interested in eight Trp Raman markers, referred to as W(i) (i = 1,...,8). All responsible for pronounced Raman lines, these markers originate from indole moiety, a bicyclic conjugated segment involved in the Trp structure. Numerous investigations have previously attempted to relate the variations observed in the spectral features of these markers to the environmental changes of Trp residues. To emphasize the most important points we can mention (i) the variations in the Raman profile of W(4) ( approximately 1360 cm(-1)) and W(5) ( approximately 1340 cm(-1)), frequently observed as a doublet with variable intensity ratio. These two markers were thought to result from a Fermi-resonance effect between certain planar and nonplanar modes; (ii) the changes observed in the wavenumbers and relative intensities of W(4), W(7) ( approximately 880 cm(-1)) and W(8) ( approximately 760 cm(-1)) were supposed to be related to the accessibility of Trp to surrounding water molecules; and (iii) the wavenumber fluctuations of W(3) ( approximately 1550 cm(-1)), taken as a Trp side chain orientational marker. However, some ambiguities still exist regarding the interpretation of these markers, needing further clarification. Herein, upon a joint experimental and theoretical analysis based on a multiconformational approach, attention was paid to the relationships between structural and vibrational features of three indole-containing compounds with increasing structural complexity, i.e., skatole (3-methylindole), tryptophan, and tripeptide Gly-Trp-Gly. This study clearly shows that the existing assignments given to certain Trp Raman markers should be reconsidered, especially those based on the Fermi-resonance origin of W(4)-W(5) ( approximately 1360-1340 cm(-1)) doublet, as well as the purely environmental dependence of W(7) and W(8) markers.
Citer cet article
Hernandez, B., Coic, Y.-M., Kruglik, S.-G., Sanchez-Cortez, S., & Ghomi, M. (2024). Relationships between conformational and vibrational features of tryptophan characteristic Raman markers. Spectrochim Acta A Mol Biomol Spectrosc, 316, Article No. 124377. https://doi.org/10.1016/j.saa.2024.124377@article{Hernandez2024_488,
author = {Hernandez, Bélen and Coic, Yves-Marie and Kruglik, Sergei G. and Sanchez-Cortez, Santiago and Ghomi, Mahmoud},
year = {2024},
month = {8},
title = {Relationships between conformational and vibrational features of tryptophan characteristic Raman markers},
journal = {Spectrochim Acta A Mol Biomol Spectrosc},
volume = {316},
pages = {Article No. 124377},
abstract = {Tryptophan (Trp) residue provides characteristic vibrational markers to the middle wavenumber spectral region of the Raman spectra recorded from peptides and proteins. In this report, we were particularly interested in eight Trp Raman markers, referred to as W(i) (i = 1,...,8). All responsible for pronounced Raman lines, these markers originate from indole moiety, a bicyclic conjugated segment involved in the Trp structure. Numerous investigations have previously attempted to relate the variations observed in the spectral features of these markers to the environmental changes of Trp residues. To emphasize the most important points we can mention (i) the variations in the Raman profile of W(4) ( approximately 1360 cm(-1)) and W(5) ( approximately 1340 cm(-1)), frequently observed as a doublet with variable intensity ratio. These two markers were thought to result from a Fermi-resonance effect between certain planar and nonplanar modes; (ii) the changes observed in the wavenumbers and relative intensities of W(4), W(7) ( approximately 880 cm(-1)) and W(8) ( approximately 760 cm(-1)) were supposed to be related to the accessibility of Trp to surrounding water molecules; and (iii) the wavenumber fluctuations of W(3) ( approximately 1550 cm(-1)), taken as a Trp side chain orientational marker. However, some ambiguities still exist regarding the interpretation of these markers, needing further clarification. Herein, upon a joint experimental and theoretical analysis based on a multiconformational approach, attention was paid to the relationships between structural and vibrational features of three indole-containing compounds with increasing structural complexity, i.e., skatole (3-methylindole), tryptophan, and tripeptide Gly-Trp-Gly. This study clearly shows that the existing assignments given to certain Trp Raman markers should be reconsidered, especially those based on the Fermi-resonance origin of W(4)-W(5) ( approximately 1360-1340 cm(-1)) doublet, as well as the purely environmental dependence of W(7) and W(8) markers.},
url = {https://www.sciencedirect.com/science/article/abs/pii/S1386142524005432},
doi = {10.1016/j.saa.2024.124377},
}TY - JOUR
AU - Hernandez, Bélen
AU - Coic, Yves-Marie
AU - Kruglik, Sergei G.
AU - Sanchez-Cortez, Santiago
AU - Ghomi, Mahmoud
PY - 2024
DA - 2024/08/05
TI - Relationships between conformational and vibrational features of tryptophan characteristic Raman markers
JO - Spectrochim Acta A Mol Biomol Spectrosc
VL - 316
AB - Tryptophan (Trp) residue provides characteristic vibrational markers to the middle wavenumber spectral region of the Raman spectra recorded from peptides and proteins. In this report, we were particularly interested in eight Trp Raman markers, referred to as W(i) (i = 1,...,8). All responsible for pronounced Raman lines, these markers originate from indole moiety, a bicyclic conjugated segment involved in the Trp structure. Numerous investigations have previously attempted to relate the variations observed in the spectral features of these markers to the environmental changes of Trp residues. To emphasize the most important points we can mention (i) the variations in the Raman profile of W(4) ( approximately 1360 cm(-1)) and W(5) ( approximately 1340 cm(-1)), frequently observed as a doublet with variable intensity ratio. These two markers were thought to result from a Fermi-resonance effect between certain planar and nonplanar modes; (ii) the changes observed in the wavenumbers and relative intensities of W(4), W(7) ( approximately 880 cm(-1)) and W(8) ( approximately 760 cm(-1)) were supposed to be related to the accessibility of Trp to surrounding water molecules; and (iii) the wavenumber fluctuations of W(3) ( approximately 1550 cm(-1)), taken as a Trp side chain orientational marker. However, some ambiguities still exist regarding the interpretation of these markers, needing further clarification. Herein, upon a joint experimental and theoretical analysis based on a multiconformational approach, attention was paid to the relationships between structural and vibrational features of three indole-containing compounds with increasing structural complexity, i.e., skatole (3-methylindole), tryptophan, and tripeptide Gly-Trp-Gly. This study clearly shows that the existing assignments given to certain Trp Raman markers should be reconsidered, especially those based on the Fermi-resonance origin of W(4)-W(5) ( approximately 1360-1340 cm(-1)) doublet, as well as the purely environmental dependence of W(7) and W(8) markers.
SP - Article No. 124377
DO - 10.1016/j.saa.2024.124377
UR - https://www.sciencedirect.com/science/article/abs/pii/S1386142524005432
ER -