Ligand environment of the S2 state of photosystem II: a study of the hyperfine interactions of the tetranuclear manganese cluster by 2D 14N HYSCORE spectroscopy.

摘要: The solar water-splitting protein complex, photosystem II, catalyzes the light-driven oxidation of water to dioxygen in Nature. four-electron reaction occurs at tetranuclear manganese—calcium—oxo catalytic cl uster that is present oxygen-evolving complex II. mechanism has been a subject intense interest, and II studied extensively by structural biochemical methods. While recent X-ray crystal structures single-crystal EXAFS investigations provide model for geometry manganese-calcium-oxo cluster, there limited knowledge environment surrounds cluster. In this study, we demonstrate application two-dimensional hyperfine sublevel correlation spectroscopy determine magnetic couplings cluster with 14 N atoms surrounding amino acid residues S 2 state We utilize difference facilitate unambiguous assignments spectral features identify least three separate are interacting state. results presented here, first time, previously unknown ligands avenues assignment site-directed mutagenesis refinement computational mechanistic models