Photochemistry of the retinal chromophore in the process of seeing (vision)

The process of vision is a complex biochemical process that involves the participation of two types of retinal photoreceptor cells: rod cells and cone cells. These visual pigments possess the chromophore, 11-cis-retinal, linked through a Schiff base linkage to the opsin protein. Absorption of light by the visual pigment leads to the photoexcitation followed by photoisomerization, 11-cis-retinal (Z) to all-trans-retinal (E) for the activation of transducin, a heterotrimeric G-protein, to generate a nerve signal that is transmitted to the brain to produce the sense of vision. The photoisomerized pigment undergoes rapid hydrolysis to produce the opsin protein and all-trans-retinal that can be reconverted enzymatically to 11-cis-retinal for recharging the opsin protein to regenerate the active visual pigment to maintain the Wald's visual cycle.

Automated summary

The process of vision involves rod and cone cells. Light excitation leads to photoisomerization, activating transducin to generate a nerve signal. Hydrolysis of the photoisomerized pigment produces opsin and all-trans-retinal, which can be converted enzymatically to 11-cis-retinal to regenerate the active visual pigment and maintain the visual cycle.