Ultrafast energy relaxation dynamics of amide I vibrations coupled with protein-bound water molecules.
basic_science · Level V
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- Record sourced from PubMed, PMID 30824834.
- Also identified by DOI 10.1038/s41467-019-08899-3 and PMC identifier 6397197.
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Abstract
The influence of hydration water on the vibrational energy relaxation in a protein holds the key to understand ultrafast protein dynamics, but its detection is a major challenge. Here, we report measurements on the ultrafast vibrational dynamics of amide I vibrations of proteins at the lipid membrane/H<sub>2</sub>O interface using femtosecond time-resolved sum frequency generation vibrational spectroscopy. We find that the relaxation time of the amide I mode shows a very strong dependence on the H<sub>2</sub>O exposure, but not on the D<sub>2</sub>O exposure. This observation indicates that the exposure of amide I bond to H<sub>2</sub>O opens up a resonant relaxation channel and facilitates direct resonant vibrational energy transfer from the amide I mode to the H<sub>2</sub>O bending mode. The protein backbone motions can thus be energetically coupled with protein-bound water molecules. Our findings highlight the influence of H<sub>2</sub>O on the ultrafast structure dynamics of proteins.