From photons to protons in the photocycle of bacterial reaction center

摘要

The detailed knowledge of the atomic coordinates of the bacterial reaction center (RC) has permitted a close scrutiny of structure/function relationships not only of the quinones but of the protein itself with its internal water structure. Protonatable groups were identified as intrinsic part of the redox reactions, providing charge compensation and forming channels for the movement of hydrogen ions to QB2-. The nature and position of these groups give rise to electrostatic profiles that determine the kinetics and energetics of proton transport. Fine tuning or dramatic variations of protein delivery pathways can adapt the photocycle to changes in bulk phase pH value, buffering capacities and primary structure of the RC.