A light-induced spin-polarized triplet detected by EPR in Photosystem II reaction centers

doi:10.1016/0005-2728(81)90020-7

Biochimica et Biophysica Acta (BBA) - Bioenergetics

Volume 635, Issue 2, 13 April 1981, Pages 205-214

https://doi.org/10.1016/0005-2728(81)90020-7 Get rights and content

Abstract

A light-induced spin-polarized triplet state has been detected in a purified Photosystem II preparation by electron paramagnetic resonance spectroscopy at liquid helium temperature.

The electron spin polarization pattern is interpreted to indicate that the triplet originates from radical pair recombination between the oxidized primary donor chlorophyll, P-680⁺, and the reduced intermediate pheophytin, I⁻, as has been previously demonstrated in bacterial reaction centers. The dependence of the triplet signal on the redox state of I and the primary acceptor, Q, are consistent with the origin of the triplet signal from the triplet state of P-680.

Redox-poising experiments indicate the presence of an endogenous donor (or donors) which operates at 3–5 K and 200 K.

The zero field-splitting parameters of the triplet are very similar to those of monomeric chlorophyll a, however, this alone does not allow a distinction to be made between monomeric and dimeric structures for P-680.

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A light-induced spin-polarized triplet detected by EPR in Photosystem II reaction centers

Abstract

Biochim. Biophys. Acta

FEBS Lett.

Biochim. Biophys. Acta

FEBS Lett.

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

FEBS lett.

FEBS Lett.

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

FEBS Lett.

FEBS Lett.

FEBS Lett.