biostudies-literatureWong SYEuropean Research CouncilDeutsche ForschungsgemeinschaftOffice of Naval Research Global975-982https://www.ebi.ac.uk/biostudies/studies/S-EPMC9811481biostudies-literatureUnknown25(2)Magnetic field effects on the yields of radical pair reactions are often characterised by the "half-field" parameter, <i>B</i>_1/2, which encodes useful information on spin relaxation, radical recombination kinetics and electron-electron couplings as well as electron-nuclear hyperfine interactions. Here we use a variety of spin dynamics simulation methods to estimate the hyperfine-only values of <i>B</i>_1/2 for the flavin-tryptophan radical pair, [FAD˙^- TrpH˙⁺], thought to be the detector in the magnetic compass sense of migratory songbirds. The main findings are: (a) in the absence of fast recombination and spin relaxation, [FAD˙^- TrpH˙⁺] radical pairs in solution and in the putative magnetoreceptor protein, cryptochrome, haPhysical chemistry chemical physics : PCCPMagnetic field effects on radical pair reactions: estimation of <i>B</i>_1/2 for flavin-tryptophan radical pairs in cryptochromes.PMC9811481SFB 137281000262909-19-1-2045Wong SYBenjamin PHore PJfalseMagnetic field effects on radical pair reactions: estimation of <i>B</i>_1/2 for flavin-tryptophan radical pairs in cryptochromes.Magnetic field effects on the yields of radical pair reactions are often characterised by the "half-field" parameter, <i>B</i>_1/2, which encodes useful information on spin relaxation, radical recombination kinetics and electron-electron couplings as well as electron-nuclear hyperfine interactions. Here we use a variety of spin dynamics simulation methods to estimate the hyperfine-only values of <i>B</i>_1/2 for the flavin-tryptophan radical pair, [FAD˙^- TrpH˙⁺], thought to be the detector in the magnetic compass sense of migratory songbirds. The main findings are: (a) in the absence of fast recombination and spin relaxation, [FAD˙^- TrpH˙⁺] radical pairs in solution and in the putative magnetoreceptor protein, cryptochrome, ha2023-01-01T00:00:00Z2023 Jan2025-04-22T15:39:38.19Z2025-04-06T01:25:14.95ZS-EPMC98114813651937910.1039/d2cp03793a