Protein-water coupling tunes the anharmonicity of amide I modes in the interfacial membrane-bound proteins
The diagonal anharmonicity of an amide I mode of protein backbones plays a critical role in a protein's vibrational dynamics and energy transfer. However, this anharmonicity of long-chain peptides and proteins in H O environment is still lacking. Here, we investigate the anharmonicity of the am...
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Published in | The Journal of chemical physics Vol. 156; no. 10; p. 105103 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
14.03.2022
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Online Access | Get more information |
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Summary: | The diagonal anharmonicity of an amide I mode of protein backbones plays a critical role in a protein's vibrational dynamics and energy transfer. However, this anharmonicity of long-chain peptides and proteins in H
O environment is still lacking. Here, we investigate the anharmonicity of the amide I band of proteins at the lipid membrane/H
O interface using a surface-sensitive pump-probe setup in which a femtosecond infrared pump is followed by a femtosecond broadband sum frequency generation vibrational spectroscopy probe. It is found that the anharmonicity of the amide I mode in ideal α-helical and β-sheet structures at hydrophobic environments is 3-4 cm
, indicating that the amide I mode in ideal α-helical and β-sheet structures is delocalized over eight peptide bonds. The anharmonicity increases as the bandwidth of the amide I mode increases due to the exposure of peptide bonds to H
O. More H
O exposure amounts lead to a larger anharmonicity. The amide I mode of the peptides with large H
O exposure amounts is localized in one to two peptide bonds. Our finding reveals that the coupling between the amide I mode and the H
O bending mode does not facilitate the delocalization of the amide I mode along the peptide chain, highlighting the impact of H
O on energy transfer and structural dynamics of proteins. |
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ISSN: | 1089-7690 |
DOI: | 10.1063/5.0078632 |