Magnetic Field Effects on Reaction Yields in the Solid State: An Example from Photosynthetic Reaction Centers

Boxer, Steven G.; Chidsey, Christopher E. D.; Roelofs, M. G.

doi:10.1146/annurev.pc.34.100183.002133

Cited by 131 publications

(97 citation statements)

References 36 publications

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“…Compared with these chemical studies, there are relatively few reliable examples of magnetic field effects on biological processes, the most notable by far being photosynthetic reaction center proteins where light absorption leads to radical pair formation by sequential electron transfer steps (reviewed in refs. [15][16][17].…”

mentioning

confidence: 99%

“…A well-studied precedent for this kind of magnetically sensitive radical pair chemistry is provided by the initial charge separation steps of bacterial photosynthetic energy conversion, which proceed via a series of radical ion pairs formed by sequential electron transfers along a chain of immobilized chlorophyll and quinone cofactors in a reaction center protein complex (15)(16)(17). Provided subsequent forward electron transfer is blocked, the recombination of the primary radical pair responds to magnetic fields in excess of Ϸ1 mT.…”

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confidence: 99%

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Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

476

449

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Migratory birds travel vast distances each year, finding their way by various means, including a remarkable ability to perceive the Earth's magnetic field. Although it has been known for 40 years that birds possess a magnetic compass, avian magnetoreception is poorly understood at all levels from the primary biophysical detection events, signal transduction pathways and neurophysiology, to the processing of information in the brain. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. Here, we present a physical chemist's perspective on the ''radical pair mechanism'' of compass magnetoreception in birds. We outline the essential chemical requirements for detecting the direction of an Earth-strength Ϸ50 T magnetic field and comment on the likelihood that these might be satisfied in a biologically plausible receptor. Our survey concludes with a discussion of cryptochrome, the photoactive protein that has been put forward as the magnetoreceptor molecule.

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confidence: 99%

mentioning

confidence: 99%

Chemical magnetoreception in birds: The radical pair mechanism

Rodgers

Hore²

2009

Proc. Natl. Acad. Sci. U.S.A.

476

449

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“…In other words, Haberkorn obtained the correct density matrix evolution equation, missing, however, the quantum jump equations (7) and their physical interpretation, as the conceptual underpinnings of quantum measurement theory and open quantum systems were lacking at the time. In Section V on the explanation of recent experimental data we will explicitly explain how the quantum dynamic evolution described by (6) and (7) is actually simulated. Thus the fundamental quantum dynamical evolution of radical-ion-pair recombination reactions is given by (6) together with (7).…”

Section: Quantum Measurement Theory Description Of Radical-ion-pmentioning

confidence: 99%

“…Radical-ion pairs, created by a charge transfer from a photo-excited donor-acceptor molecular dyad, are central in the reaction chain taking place in the photosynthetic reaction center [5,6]. The magnetic interactions [7,8] of the two unpaired electrons in the radical-ionpair with external magnetic fields and internal hyperfine magnetic fields add another layer of complexity in the charge-transfer chain-reactions that convert the absorbed photon energy to chemical energy vital for further biological function.…”

Section: Introductionmentioning

confidence: 99%

Quantum Zeno effect explains magnetic-sensitive radical-ion-pair reactions

Kominis

2009

Phys. Rev. E

107

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Chemical reactions involving radical-ion pairs are ubiquitous in biology, since not only are they at the basis of the photosynthetic reaction chain, but are also assumed to underlie the biochemical magnetic compass used by avian species for navigation. Recent experiments with magnetic-sensitive radical-ion pair reactions provided strong evidence for the radical-ion-pair magnetoreception mechanism, verifying the expected magnetic sensitivities and chemical product yield changes. It is here shown that the theoretical description of radical-ion-pair reactions used since the 70's cannot explain the observed data, because it is based on phenomenological equations masking quantum coherence effects. The fundamental density matrix equation derived here from basic quantum measurement theory considerations naturally incorporates the quantum Zeno effect and readily explains recent experimental observations on low-and high-magnetic-field radical-ion-pair reactions.

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“…The direction of this effect, and the unusual spin polarization seen in the EPR spectrum showed clearly that P + BPh − was created initially in a singlet state. Further studies of the effects of magnetic fields by the late Arnold Hoff, and by Mary Elizabeth (Maibi) Michel-Beyerle, Klaus Schulten, Steven (Steve) Boxer, Marion Thurnauer, Jim Norris, and their coworkers unearthed a rich source of information on the electronic coupling and energetics of the P + and BPh − radicals, and led to some of the initial suggestions that there might be still another electron carrier between P and the BPh (see, e.g., Thurnauer et al 1975;Hoff et al 1977;Haberkorn and Michel-Beyerle 1977;Werner et al 1978;Haberkorn et al 1979;Boxer 1983). In reaction centers that contained carotenoids, the BChl triplet state decayed on nanosecond time scales by transferring energy to a carotenoid Parson and Monger 1976;Shuvalov and Klimov 1976).…”

Section: Electron Acceptorsmentioning

confidence: 99%

Electron donors and acceptors in the initial steps of photosynthesis in purple bacteria: a personal account

Parson

Discoveries in Photosynthesis

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The discovery by Louis N. M. Duysens in the 1950s that illumination of photosynthetic purple bacteria can cause oxidation of either a bacteriochlorophyll complex (P) or a cytochrome was followed by an extended period of uncertainty as to which of these processes was the 'primary' photochemical reaction. Similar questions arose later about the roles of bacteriopheophytin (BPh) and quinones as the initial electron acceptor. This is a personal account of kinetic measurements that showed that electron transfer from P to BPh occurs in the initial step, and that the oxidized bacteriochlorophyll complex (P + ) then oxidizes the cytochrome while the reduced BPh transfers an electron to a quinone.Abbreviations: BChl -bacteriochlorophyll; P -the BChl complex that serves as electron donor in the initial electron-transfer step of photosynthesis in purple bacteria; P + -the oxidized form of P The primary electron donorAs a predoctoral student at

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Magnetic Field Effects on Reaction Yields in the Solid State: An Example from Photosynthetic Reaction Centers

Cited by 131 publications

References 36 publications

Chemical magnetoreception in birds: The radical pair mechanism

Chemical magnetoreception in birds: The radical pair mechanism

Quantum Zeno effect explains magnetic-sensitive radical-ion-pair reactions

Electron donors and acceptors in the initial steps of photosynthesis in purple bacteria: a personal account

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