Electron transfer and spin exchange contributing to the magnetic field dependence of the primary photochemical reaction of bacterial photosynthesis

doi:10.1016/0005-2728(78)90047-6

Biochimica et Biophysica Acta (BBA) - Bioenergetics

Volume 502, Issue 2, 10 May 1978, Pages 255-268

https://doi.org/10.1016/0005-2728(78)90047-6 Get rights and content

Abstract

The yield ϕ_T of triplet products “P_R” generated in reaction centers of Rhodopseudomonas sphaeroides in which the “primary” acceptor is reduced had been found to depend on external magnetic fields. The magnetic field dependence varies, however, between different reaction center preparations. By means of a theoretical description of the primary electron transfer processes and hyperfine coupling-induced electron spin motion the factors influencing the magnetic field behaviour of the triplet products are studied. The following quantities characteristic of the primary electron transfer in photosynthesis have a strong effect on ϕ_T: (1) the rate constants of reversible electron transfer between the initially excited singlet state of the reaction center and an intermediate radical ion pair state; (2) the rate constants of irreversible electron transfer of the radical pair to the ground and excited triplet state of the reaction center; (3) the electron exchange interactions between the radical pair and the “primary” acceptor. From the observed magnetic field dependence of ϕ_T estimates for these quantities are obtained. A temperature dependence of the magnetic field behaviour of ϕ_T and a magnetic field effect on the fluorescence quantum yield of the reaction center are predicted.

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^∗: Present address: Institut für physikalische und theoretische Chemie der Universität Frankfurt/M, Robert-Mayer-Str. 11, 6000 Frankfurt/M, German Federal Republic.

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Electron transfer and spin exchange contributing to the magnetic field dependence of the primary photochemical reaction of bacterial photosynthesis

Abstract

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Biochim. Biophys. Acta

FEBS Lett.

Biochem. Biophys. Res. Commun.

Biochim. Biophys. Acta

Biochim. Biophys. Acta

Chem. Phys.

Chem. Phys. Lett.

FEBS Lett.

Biochim. Biophys. Acta

FEBS Lett.

Biochim. Biophys. Acta

Biochim. Biophys. Acta