An additional water is introduced into the manganese cluster during the formation of the S(3) state of photosystem II.
- Open access
High-resolution data confirm the addition of a new water-derived oxygen atom during the S3 state of photosystem II’s manganese cluster, with no evidence of O-O bond formation at this stage.
- Why it matters: Understanding the precise timing and mechanism of water oxidation is crucial for elucidating photosynthetic oxygen evolution, which has implications for artificial photosynthesis and renewable energy.
- What they did: The study used ~1.9 Å resolution X-ray crystallography and anomalous diffraction at two energies to model manganese and oxygen positions, identifying a new oxygen ligand in the S3 state.
- The result: Findings show the new oxygen binds to Mn1 and Ca without forming an O-O bond in S3, implying that O-O bond formation likely occurs during the subsequent S3 to S0 transition.