Absence of a link between stabilized charge-separated state and structural changes proposed from crystal structures of a photosynthetic reaction center.

ABSTRACT: Structural differences between illuminated and unilluminated crystal structures led to the proposal that the charge-separated state was stabilized by structural changes in its membrane extrinsic protein subunit H in a bacterial photosynthetic reaction center [Katona, G. et al. Nat. Struct. Mol. Biol. 2005, 12, 630-631]. Here, we explored the proposal by titrating all titratable sites and calculating the redox potential (E_m) values in these crystal structures. Contrary to the expected charge-separated states, E_m for quinone, E_m(Q_A/Q_A^•-), is even lower in the proposed charge-separated structure than in the ground-state structure. The subunit-H residues, which were proposed to exhibit electron-density changes in the two crystal

SUBMITTER: Noji T 

PROVIDER: S-EPMC11364808 | biostudies-literature | 2024 Aug

REPOSITORIES: biostudies-literature