Intense chiral signal from α-helical poly-L-alanine observed in low-frequency Raman optical activity

0549139 - ÚOCHB 2022 RIV GB eng J - Článek v odborném periodiku
Yamamoto, S. - Ishiro, S. - Kessler, Jiří - Bouř, Petr
Intense chiral signal from α-helical poly-L-alanine observed in low-frequency Raman optical activity.
Physical Chemistry Chemical Physics. Roč. 23, č. 46 (2021), s. 26501-26509. ISSN 1463-9076. E-ISSN 1463-9084
Grant CEP: GA ČR(CZ) GA20-10144S; GA MŠMT(CZ) EF16_019/0000729
Institucionální podpora: RVO:61388963
Klíčová slova: vibrational circular dichroism * molecular dynamics clusters * property tensors
Obor OECD: Physical chemistry
Impakt faktor: 3.945, rok: 2021
Způsob publikování: Omezený přístup
https://doi.org/10.1039/D1CP04401J

Raman optical activity (ROA) spectral features reliably indicate the structure of peptides and proteins, but the signal is often weak. However, we observed significantly enhanced low-frequency bands for α-helical poly-L-alanine (PLA) in solution. The biggest ROA signal at ∼100 cm−1 is about 10 times stronger than higher-frequency bands described previously, which facilitates the detection. The low-frequency bands of PLA were compared to those of α-helical proteins. For PLA, density functional simulations well reproduced the experimental spectra and revealed that about 12 alanine residues within two turns of the α-helix generate the strong ROA band. Averaging based on molecular dynamics (MD) provided an even more realistic spectrum compared to the static model. The low-frequency bands could be largely related to a collective motion of the α-helical backbone, partially modulated by the solvent. Helical and intermolecular vibrational coordinates have been introduced and the helical unwinding modes were assigned to the strongest ROA signal at 101–128 cm−1. Further analysis indicated that the helically arranged amide and methyl groups are important for the strong chiral signal of PLA, while the local chiral centers CαH contribute in a minor way only. The strong low-frequency ROA can thus provide precious information about the motions of the peptide backbone and facilitate future protein studies.
Trvalý link: http://hdl.handle.net/11104/0325156