A relationship between the midpoint potential of the primary acceptor and low temperature photochemistry in photosystem II
- 18 April 1983
- journal article
- Published by Wiley in FEBS Letters
- Vol. 154 (2) , 328-334
- https://doi.org/10.1016/0014-5793(83)80176-8
Abstract
Redox titrations of the photo‐induced pheophytin EPR signal in Photosystem II show two transitions which reflect the redox state of Q. The high potential wave (Em⋍ −50 mV) can be photo‐induced at 5 K and 77 K. The low potential wave (Em⋍ −275 mV) required illumination at 200 K. This indicates the presence of two kinds of PS‐II reaction centres differing in terms of the competence of their donors at low temperature and theEm‐values of their acceptors. Measurements of the semiquinone‐iron acceptor also demonstrate functional heterogeneity at low temperature. This is the first observation of the semiquinone‐iron acceptor in a non‐mutant species.Keywords
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