jz8b01528_si_001.pdf (13.94 MB)
Absorption Spectra of FAD Embedded in Cryptochromes
journal contribution
posted on 2018-06-15, 00:00 authored by Claus Nielsen, Morten S. Nørby, Jacob Kongsted, Ilia A. Solov’yovThe magnetic compass sense utilized
by migratory birds for long-distance
navigation functions only once light of a certain wavelength is present.
This piece of evidence fits partially with the popular hypothesis
of chemical magnetoreception in cryptochrome proteins, located in
the bird retina. According to this hypothesis a magnetosensitive radical
pair is produced after photoexcitation of an FAD cofactor inside cryptochrome,
and as such the absorption properties of FAD are of crucial importance
for cryptochrome activation. However, we reveal that absorption spectra
of FAD show very little variation between six different cryptochromes,
suggesting that the electronic transitions are barely affected by
the chemical differences in the proteins. This conclusion hints on
the presence of a secondary photoreceptor or cofactor that could be
necessary to explain green-light-activated magnetoreception in birds.