Nohr, D., Paulus, B., Rodriguez, R., Okafuji, A., Bittl, R., Schleicher, E., Weber, S. (2017). Determination of Radical-Radical Distances in Light-Active Proteins and Their Implication for Biological Magnetoreception.  Angew. Chem. Int. Ed. Engl. 56(29): 8550--8554.

FBrf0235953

Research paper

Light-generated short-lived radial pairs have been suggested to play pivotal roles in cryptochromes and photolyases. Cryptochromes are very probably involved in magnetic compass sensing in migratory birds and the magnetic-field-dependent behavior of insects. We examined photo-generated transient states in the cryptochrome of Drosophila melanogaster and in the structurally related DNA-repair enzyme Escherichia coli DNA photolyase. Using pulsed EPR spectroscopy, the exchange and dipolar contributions to the electron spin-spin interaction were determined in a straightforward and direct way. With these parameters, radical-pair partners may be identified and the magnetoreceptor efficiency of cryptochromes can be evaluated. We present compelling evidence for an extended electron-transfer cascade in the Drosophila cryptochrome, and identified W394 as a key residue for flavin photoreduction and formation of a spin-correlated radical pair with a sufficient lifetime for high-sensitivity magnetic-field sensing.