JMS/sandbox22: Difference between revisions

Illia Solov'yov and Klau Schulten of UIUC think that the FAD factor and just several residues of a crytochrome protein is all it takes to register the magnetic field of the earth. The <scene name='58/585079/1u3d_magnet/2'>"magnetic core"</scene> they describe involves the <scene name='58/585079/1u3d_magnet/15'>FAD factor, three tryptophan residues, as well as the aspartic residues which neighbor the FAD factor</scene>. When light in the blue range hits the FAD factor it becomes excited, with the excitement diffused over its <scene name='58/585079/1u3d_magnet/10'>aromatic ring system</scene>. Then, one of the three neighboring aspartic acid residues donates a hydrogen proton from its hydroxyl group. The FAD factor then receives an electron from the neighboring tryptophan, from the tryptophan's nitrogen atom (shown in halo). The proton and electron that FAD received are attached to one of the nitrogen atoms on its ring (shown in halos). Next, this tryptophan received an electron from its <scene name='58/585079/1u3d_magnet/11'>neighboring tryptophan</scene>, and then the second tryptophan received an electron from its neighbor, a third tryptophan. Finally, the third tryptophan loses a proton to a neighboring element. At the end of this reaction, both the FAD factor and the third tryptophan residue contain a unpaired electron. The ability of the FAD factor to transfer back the electron received from the first trytophan to the third tryptophan is effected by the magnetic field of the Earth, because the two electons can exist in two spin states, parallel and antiparallel, with interconversion between states partly determined by the earth's magnetic force, and only the parallel state compatible with back transfer of the electron from FAD to trytophan. Thus, the speed which with FAD transfers back its donated electron is affected by the earth's magnetic field, and that speed can be registered by the brain as a proxy for where it lies relative to the earth's magnetic field.