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Photoreceptor proteins are light-sensitive proteins involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cells of the vertebrate retina , phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacteria .
Proteins known as opsins form the crux of the photosensitive proteins. These proteins are often found in the eye. In addition, many of these proteins function as ion channels and receptors. One example is when a certain wavelength of light is put onto certain channels, the blockage in the pore is relieved and allows ion transduction. [6]
Photosensitive drug reaction secondary to medications may cause phototoxic, photoallergic, and lichenoid reactions, and photodistributed telangiectasias, as well as pseudoporphyria. [ 1 ] : 121 Drugs involved include naproxen and doxycycline .
A photolabile protecting group (PPG; also known as: photoremovable, photosensitive, or photocleavable protecting group) is a chemical modification to a molecule that can be removed with light. PPGs enable high degrees of chemoselectivity as they allow researchers to control spatial, temporal and concentration variables with light.
Photopharmacology is an emerging multidisciplinary field that combines photochemistry and pharmacology. [1] Built upon the ability of light to change the pharmacokinetics and pharmacodynamics of bioactive molecules, it aims at regulating the activity of drugs in vivo by using light. [2]
Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicity .
The pigments in photoreceptor proteins either change their conformation or undergo photoreduction when they absorb a photon. [3] This change in the conformation or redox state of the chromophore then affects the protein conformation or activity and triggers a signal transduction cascade. [3] Examples of photoreceptor pigments include: [4]
Rhodopsin is made constitutively (continuously) active by some of those mutations even without light. [45] [46] [47] Also wild-type rhodopsin is constitutively active, if no 11-cis-retinal is bound, but much less. [48] Therefore 11-cis-retinal is an inverse agonist. Such mutations are one cause of autosomal dominant retinitis pigmentosa. [47]