Mechanism of Mixed-Valence Fe^2.5+···Fe^2.5+ Formation in Fe₄S₄ Clusters in the Ferredoxin Binding Motif.

ABSTRACT: Most low-potential Fe₄S₄ clusters exist in the conserved binding sequence CxxCxxC (CⁿCⁿ⁺³Cⁿ⁺⁶). Fe(II) and Fe(III) at the first (Cⁿ) and third (Cⁿ⁺⁶) cysteine ligand sites form a mixed-valence Fe^2.5+···Fe^2.5+ pair in the reduced Fe(II)₃Fe(III) cluster. Here, we investigate the mechanism of how the conserved protein environment induces mixed-valence pair formation in the Fe₄S₄ clusters, F_X, F_A, and F_B in photosystem I, using a quantum mechanical/molecular mechanical approach. Exchange coupling between Fe sites is predominantly determined by the shape of the Fe₄S₄ cluster,

SUBMITTER: Kanda T 

PROVIDER: S-EPMC9059760 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature