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Unusual Vibrational Coupling of the Schiff Base in the Retinal Chromophore of Sodium Ion-Pumping Rhodopsins.

Taiki NakamuraYuka ShinozakiAkihiro OtomoTaito UruiMisao MizunoRei Abe-YoshizumiManami HashimotoKeiichi KojimaYuki SudoHideki KandoriYasuhisa Mizutani
Published in: The journal of physical chemistry. B (2024)
A Schiff base in the retinal chromophore of microbial rhodopsin is crucial to its ion transport mechanism. Here, we discovered an unprecedented isotope effect on the C═N stretching frequency of the Schiff base in sodium ion-pumping rhodopsins, showing an unusual interaction of the Schiff base. No amino acid residue attributable to the unprecedented isotope effect was identified, suggesting that the H-O-H bending vibration of a water molecule near the Schiff base was coupled with the C═N stretching vibration. A twist in the polyene chain in the chromophore for the sodium ion-pumping rhodopsins enabled this unusual interaction of the Schiff base. The present discovery provides new insights into the interaction network of the retinal chromophore in microbial rhodopsins.
Keyphrases
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  • amino acid
  • microbial community
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  • high resolution
  • molecular dynamics
  • quantum dots