An Update to Expression and Purification of Cryptochrome IV from Bacterial Cultures

Abstract

The navigational abilities of birds have been observed throughout history, yet the ability of living organisms, including migratory birds, possessing the ability to detect the Earth’s magnetic field has only been largely discussed and researched in the past 60 years. Evidence has supported the conclusion that migratory birds can detect the Earth’s magnetic field, and its direction, but the exact mechanism is yet to be agreed upon by scientists. One of the theories regarding the magnetoreception in avian species that correlates with the detection of the Earth’s magnetic field is The Radical Pair Model involving cryptochrome (CRY) protein and light-dependent photoreduction. In CRY4 (magnetic-sensing cryptochrome), blue light is absorbed by a bound flavin adenine dinucleotide (FAD) chromophore, generating a radical spin pair (quantum mechanical) between FAD and tryptophan (W).3,4 The Radical Pair Model introduces a dipole moment between the two charged radicals (i.e., magnet) that will be sensitive to the magnetic field. The propagation of the radicals along a W chain is expected to promote a conformational change in the protein to induce signaling. The aim of this research is to further investigate the radical pair mechanism in CRY4 and its work in conjunction to promote the upregulation of photoreduction necessary for migratory birds to sense directional changes in the Earth’s magnetic field. Further, it can help shed light onto how Biology has adapted to use quantum mechanical phenomena for function.