Interaction of spin-correlated radical pair with a third radical: Combined effect of spin-exchange interaction and spin-selective reaction

Bagryansky, V. A.; Borovkov, V. I.; Bessmertnykh, Alena; Tretyakova, Irina S.; Beregovaya, I. V.; Molin, Yuri N.

doi:10.1063/1.5127812

Cited by 5 publications

(6 citation statements)

References 30 publications

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“…Alternatively, the effects of stable free radicals on the MFEs could be probed. Experiments investigating this kind spin chemistry are being increasingly pursued. , It will be necessary to ensure three-radical correlation rather than plainly exposing radical pairs to (multiple) scavenger radicals, which would abolish the MFEs . Thus, a certain degree of compartmentalization (e.g., in micelles), association (e.g., scavenger radical binding), or reduction of translational mobility will be required.…”

Section: Discussionmentioning

confidence: 99%

Radical Scavenging Could Answer the Challenge Posed by Electron–Electron Dipolar Interactions in the Cryptochrome Compass Model

Babcock

Kattnig

2021

JACS Au

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Many birds are endowed with a visual magnetic sense that may exploit magnetosensitive radical recombination processes in the protein cryptochrome. In this widely accepted but unproven model, geomagnetic sensitivity is suggested to arise from variations in the recombination rate of a pair of radicals, whose unpaired electron spins undergo coherent singlet–triplet interconversion in the geomagnetic field by coupling to nuclear spins via hyperfine interactions. However, simulations of this conventional radical pair mechanism (RPM) predicted only tiny magnetosensitivities for realistic conditions because the RPM’s directional sensitivity is strongly suppressed by the intrinsic electron–electron dipolar (EED) interactions, casting doubt on its viability as a magnetic sensor. We show how this RPM-suppression problem is overcome in a three-radical system in which a third “scavenger” radical reacts with one member of the primary pair. We use this finding to predict substantial magnetic field effects that exceed those of the RPM in the presence of EED interactions in animal cryptochromes.

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Section: Discussionmentioning

confidence: 99%

Radical Scavenging Could Answer the Challenge Posed by Electron–Electron Dipolar Interactions in the Cryptochrome Compass Model

Babcock

Kattnig

2021

JACS Au

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“…Such encounters lead to a loss, perhaps a partial loss, of the spin coherence of the RIPs, which can also be considered as an additional spin–lattice relaxation process. 18,19…”

Section: Resultsmentioning

confidence: 99%

“…This made it possible to observe the decay of paramagnetic particles reacting with oxygen and, simultaneously, to probe spin degrees of freedom of the particles involved in the reaction by observing reactioninduced decoherence of those RIPs where the reaction does not occur due to spin mismatch. 18,19 II. Results…”

Section: Introductionmentioning

confidence: 99%

A spin statistical factor in electron transfer to oxygen molecules

Borovkov

Bagryansky

Molin

2023

Phys. Chem. Chem. Phys.

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“…This suggests that the radical-radical process could be sustained as the dominant reaction pathway in an environment rich in adsorbate. In fact, a too large A •− concentration is detrimental, as the degenerate mutual exchange of A •− during the reaction event would induce further spin relaxation and reduce the magnetosensitivity [ 54 , 55 ]. Ultimately, this implies that the practical feasibility of the model hinges on the right kinetics and concentrations.…”

Section: Discussionmentioning

confidence: 99%

Radical triads, not pairs, may explain effects of hypomagnetic fields on neurogenesis

Jess

Kattnig

2022

PLoS Comput Biol

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Adult hippocampal neurogenesis and hippocampus-dependent cognition in mice have been found to be adversely affected by hypomagnetic field exposure. The effect concurred with a reduction of reactive oxygen species in the absence of the geomagnetic field. A recent theoretical study suggests a mechanistic interpretation of this phenomenon in the framework of the Radical Pair Mechanism. According to this model, a flavin-superoxide radical pair, born in the singlet spin configuration, undergoes magnetic field-dependent spin dynamics such that the pair’s recombination is enhanced as the applied magnetic field is reduced. This model has two ostensible weaknesses: a) the assumption of a singlet initial state is irreconcilable with known reaction pathways generating such radical pairs, and b) the model neglects the swift spin relaxation of free superoxide, which abolishes any magnetic sensitivity in geomagnetic/hypomagnetic fields. We here suggest that a model based on a radical triad and the assumption of a secondary radical scavenging reaction can, in principle, explain the phenomenon without unnatural assumptions, thus providing a coherent explanation of hypomagnetic field effects in biology.

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Interaction of spin-correlated radical pair with a third radical: Combined effect of spin-exchange interaction and spin-selective reaction

Cited by 5 publications

References 30 publications

Radical Scavenging Could Answer the Challenge Posed by Electron–Electron Dipolar Interactions in the Cryptochrome Compass Model

Radical Scavenging Could Answer the Challenge Posed by Electron–Electron Dipolar Interactions in the Cryptochrome Compass Model

A spin statistical factor in electron transfer to oxygen molecules

Radical triads, not pairs, may explain effects of hypomagnetic fields on neurogenesis

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