1H Hyperfine Interactions in the Mn-Cluster of Photosystem II in the S2 State Detected by Hyperfine Sublevel Correlation Spectroscopy

A study of the hydrogen hyperfine couplings of the Mn-cluster of the oxygen-evolving complex of Photosystem II in the S-2 state of the Kok cycle by means of hyperfine sublevel correlation spectroscopy was achieved. Features corresponding to hyperfine interaction of at least two hydrogen nuclei were detected. Combining our results with previous ENDOR data, hyperfine constants were determined, and by using a model for the structure and electronic spin state of the Mn-cluster, relevant structural information of the S-2 state was obtained. This new information can be used for improving our knowledge about the structure and function of the Mn-cluster during light-driven water oxidation reaction in oxygenic photosynthetic organisms.