 |
One million biochemical events occur in ~100 ns, leading to an optic nerve impulse to the brain. Photon capture is 60% efficient - 36 kcals/mole of energy released per photon . With bacteriorhodopsin (bR), the incidence of one photon on the retinal chromophore results in the transport and release of one proton. Thus, where bR is tethered to nanotubules, nanowires, or etched wells, detection of change in H+ concentration may provide a sub-nsecond optical switch. |
Photoreceptor Proteins
Photoreceptors, such as bacteriorhodopsin or rhodopsin, may be tethered to a conducting substratum and their sensitivity to light exploited in the production of holographic devices, detectors and nanometer photoswitches.
In rhodopsin, one photon of light isomerizes retinal (red to blue in the image opposite), functioning as a nanoswitch with a movement of ~0.2 - 0.3nm within the protein.. The process takes 0.1ns, leading to an activation of the protein through conformational changes.
Here, a model of photoisomers of retinal between dark and MetaI states is show.
