Retinaldehyde

**Definition:** A diterpene derived from the carotenoid VITAMIN A which functions as the active component of the visual cycle. It is the prosthetic group of RHODOPSIN (i.e., covalently bonded to ROD OPSIN as 11-cis-retinal). When stimulated by visible light, rhodopsin transforms this cis-isomer of retinal to the trans-isomer (11-trans-retinal). This transformation straightens-out the bend of the retinal molecule and causes a change in the shape of rhodopsin triggering the visual process. A series of energy-requiring enzyme-catalyzed reactions convert the 11-trans-retinal back to the cis-isomer.

**Tree numbers:** - D02.047.850 - D02.455.326.271.665.202.495.690 - D02.455.426.392.368.367.379.249.700.690 - D02.455.849.131.495.690 - D02.455.849.291.605 - D23.767.261.700.690

**Synonyms:** - Retinene - Retinyl Aldehydde - Axerophthal - Retinal - 3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2,4,6,8-Nonatetraenal - Vitamin A Aldehyde