Hydroxide Ion Carrier for Proton Pumps in Bacteriorhodopsin: Primary Proton Transfer

Junichi Ono, Minori Imai, Yoshifumi Nishimura, Hiromi Nakai*


研究成果: Article査読

10 被引用数 (Scopus)


Bacteriorhodopsin (BR) is a model protein for light-driven proton pumps, where the vectorial active proton transport results in light-energy conversion. To clarify the microscopic mechanism of primary proton transfer from retinal Schiff base (SB) to Asp85 in BR, herein, we performed quantum-mechanical metadynamics simulations with the isolated BR model (∼3750 atoms). The simulations showed a novel proton transfer mechanism, viz. the hydroxide ion mechanism, in which the deprotonation of specific internal water (Wat452) yields the protonation of Asp85 via Thr89, after which the resulting hydroxide ion accepts the remaining proton from retinal SB. Systematic investigations adopting four sequential snapshots obtained by the time-resolved serial femtosecond crystallography revealed that proton transfer took 2-5.25 μs on the photocycle. The presence of Wat401, which is the main difference between snapshots at 2 and 5.25 μs, is found to be essential in assisting the primary proton transfer. Furthermore, the hydroxide ion mechanism was confirmed by the minimum energy path for the primary proton transfer in BR obtained by the nudged elastic band calculations with the embedded BR model (10,119 atoms), in which BR was embedded within lipid membranes in between water solvents.

ジャーナルJournal of Physical Chemistry B
出版ステータスPublished - 2020 10月 1

ASJC Scopus subject areas

  • 物理化学および理論化学
  • 表面、皮膜および薄膜
  • 材料化学


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