Molecular Structure Related to an = 5/2 High-Spin S State Manganese Cluster of Photosystem II Investigated by Q-Band Pulse EPR Spectroscopy.

The high-spin S state of the photosynthetic oxygen-evolving cluster MnCaO, corresponding to the = 4.1 signal for X-band electron paramagnetic resonance (EPR), was investigated using Q-band pulsed EPR, which detected a main peak at = 3.10 and satellite peaks at 5.