A new paramagnetic hyperfine structure effect in manganese tetramers. The origin of “multiline” EPR signals from an S2 state of a photosynthetic water-splitting enzyme
✍ Scribed by Masami Kusunoki
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- English
- Weight
- 766 KB
- Volume
- 197
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
A new theory of EPR spectra for singlet states of Mn tetramers, allowing spin-hybridizations for component composite spins, is developed to elucidate the origin of the "multiline" EPR signals from the Mn clusters in an S2 state of photosystem II. By computer simulation it is shown that the Mn cluster most probably exists in the Mn (III, IV, IV, IV) oxidation state with a strongantiferromagnetic exchange interaction (Jab&*&,) between a pair of Mn(II1) and Mn( IV) ions and the other weak or intermediateonessatisfyingtherelations, (3/2)p,, (2&-ZJ.,+J,-J,) cos213= [Jcd-Jac-Jad+f (Jh+JW)] sin26>0, wherep,,= 1.291 and 0, a polar angle of the spin-state vector in the x-y plane of S,,=O and Scd= 1 spin configurations, is z 38"-39" in control samples.