Electronic structure of the P700 special pair from high-frequency electron paramagnetic resonance spectroscopy

Oleg G. Poluektov, Lisa M. Utschig, Sandra L. Schlesselman, K. V. Lakshmi, Gary W Brudvig, Gerd Kothe, Marion C. Thurnauer

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34 Citations (Scopus)

Abstract

Enhanced spectral resolution of high-frequency electron paramagnetic resonance (EPR) spectroscopy allows for detailed g-tensor analysis of the active paramagnetic pigments in photosynthetic reaction centers. This analysis has been made for the cation radical and triplet state of the primary donor in photosystem I (P700) compared to the same species from chlorophyll a (Chla) in vitro. The data prove that the electronic structures of the primary donor cation and triplet state are very different from those of monomeric Chla. The g-value anisotropy of P700 is smaller, and the gz component considerably deviates from that of Chla. The triplet state of P700 is also different from ChlaT. In the present study, this difference is resolved because of the high g-value resolution of the high-frequency EPR and characterized by the switching of the directions of the X and Y g-tensor axes with respect to the zero-field axes. These results can be explained either by a delocalized electronic character of the P700 and P700 T states or by a heteromeric model of the primary donor in photosystem I.

Original languageEnglish
Pages (from-to)8911-8916
Number of pages6
JournalJournal of Physical Chemistry B
Volume106
Issue number35
DOIs
Publication statusPublished - Sep 5 2002

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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    Poluektov, O. G., Utschig, L. M., Schlesselman, S. L., Lakshmi, K. V., Brudvig, G. W., Kothe, G., & Thurnauer, M. C. (2002). Electronic structure of the P700 special pair from high-frequency electron paramagnetic resonance spectroscopy. Journal of Physical Chemistry B, 106(35), 8911-8916. https://doi.org/10.1021/jp021465+