enzyme Name retinal isomerase EC number 5.2.1.3 CAS number 9023 76 1 IUBMB EC number 5 2 1 3 GO code 0004744 image width caption In enzymology , a retinal isomerase EC number 5.2.1.3 is an enzyme that catalysis catalyzes the chemical reaction all trans retinal math rightleftharpoons math 11 cis retinal Hence, this enzyme has one substrate biochemistry substrate , all trans retinal , and one product chemistry product , 11 cis retinal . This enzyme belongs to the family of isomerase s, specifically Cis trans isomerism cis trans isomerases . The systematic name of this enzyme class is all trans retinal 11 cis trans isomerase . Other names in common use include retinene isomerase , and retinoid isomerase . This enzyme participates in retinol metabolism . References reflist 1 cite journal author HUBBARD R date 1956 title Retinene isomerase journal J. Gen. Physiol. volume 39 pages 935&ndash 62 pmid 13346046 doi 10.1085 jgp.39.6.935 issue 6 pmc 2147571 cite journal author Shichi H, Somers RL date 1974 title Possible involvement of retinylidene phospholipid in photoisomerization of all trans retinal to 11 cis retinal journal J. Biol. Chem. volume 249 pages 6570&ndash 7 pmid 4472816 issue 20 isomerase stub Category EC 5.2.1 Category Enzymes of unknown structure ... more details
, with maleic acid and with azobenzene often by photoisomerization . An example is the photochemical conversion of the trans isomer to the cis isomer of resveratrol ref Resveratrol Photoisomerization ... 400px Resveratrol photoisomerization Aldose ketose isomerization Aldose ketose isomerism in biochemistry ... more details
Bacteriorhodopsin is a protein used by Archaea , the most notable one being Halobacteria . It acts as a proton pump that is, it captures light energy and uses it to move proton s across the membrane out of the cell. ref name isbn0 471 19350 X cite book author Voet, Judith G. Voet, Donald title Biochemistry publisher J. Wiley & Sons location New York year 2004 pages isbn 0 471 19350 X oclc doi accessdate ref The resulting proton gradient is subsequently converted into chemical energy. ref name urlBacteriorhodopsin Pumping Ions cite web url http www.als.lbl.gov als science sci archive rhodopsin.html title Bacteriorhodopsin Pumping Ions format work accessdate ref Bacteriorhodopsin is an integral membrane protein usually found in two dimensional crystalline patches known as purple membrane , which can occupy up to nearly 50 of the surface area of the archaeal cell. The repeating element of the hexagonal lattice is composed of three identical protein chains, each rotated by 120 degrees relative to the others. Each chain has seven transmembrane helix transmembrane alpha helices and contains one molecule of retinal buried deep within, the typical structure for retinylidene protein s. Image Bacteriorhodopsin conformation change.gif thumb right 300px Conformational change It is the retinal molecule that changes its conformation when absorbing a photon , resulting in a conformational change of the surrounding protein and the proton pumping action. ref name pmid12944261 cite journal author Hayashi S, Tajkhorshid E, Schulten K title Molecular dynamics simulation of bacteriorhodopsin s photoisomerization using ab initio forces for the excited chromophore journal Biophysical Journal volume 85 issue 3 pages 1440 9 year 2003 month September pmid 12944261 pmc 1303320 doi 10.1016 S0006 3495 03 74576 7 url http linkinghub.elsevier.com retrieve pii S0006 3495 03 74576 7 ref It is covalently linked to Lys216 in the chromophore by Schiff base action. After photoisomerization of the retin ... more details
Solar chemical refers to a number of possible processes that harness solar energy by absorbing sunlight in a Photoelectrochemical cell chemical reaction in a way similar to photosynthesis in plants but without using living organisms. It is also called artificial photosynthesis . ref Magnuson A et al. Biomimetic and Microbial Approaches to Solar Fuel Generation. Accounts of Chemical Research 2009 42 12 1899 1908 ref No practical process has yet emerged. A promising approach is to use focused sunlight to provide the energy needed to split water into its constituent hydrogen and oxygen in the presence of a metallic catalyst such as zinc . This is normally done in a two step process so that hydrogen and oxygen are not produced in the same chamber leading to potentially explosive consequences. It is also possible to use solar light to drive industrial chemical reactions and applications without a requirement for fossil fuel. Sunlight energy storing chemicals Photodimerization is the light induced formation of Dimer chemistry dimer s. As early as 1909, the dimerization of anthracene into dianthracene was investigated as a means of storing solar energy. The photodimerization of the naphthalene series has also been investigated. ref cite book author Bolton, James year 1977 title Solar Power and Fuels publisher Academic Press, Inc. isbn 0121123502 , p. 235 237 ref Image Anthracene Photodimerisation.svg thumb left 320px Anthracene dimerization clear left Photoisomerization is the light induced formation of isomer s. Various ketones, azepines and norbornadiene s among other compounds have been investigated as potential energy storing isomers. ref cite book author Bolton, James year 1977 title Solar Power and Fuels publisher Academic Press, Inc. isbn 0121123502 , p. 238 240 ref The norbornadiene quadricyclane couple is of most potential interest for solar energy storage processes. The controlled release of the strain energy stored in quadricyclane about 110 k joule per mole J m ... more details
About molecular photoreceptors other types of photoreceptors Photoreceptor disambiguation Refimprove date March 2007 Photoreceptors are light sensitive protein s involved in the sensing and response to light in a variety of organisms. Some examples are rhodopsin in the photoreceptor cell s of the vertebrate retina , phytochrome in plants, and bacteriorhodopsin and bacteriophytochromes in some bacterium bacteria . They mediate light responses as varied as visual perception , phototropism and phototaxis , as well as responses to light dark cycles such as circadian rhythm and other photoperiodism s including control of flowering times in plants and mating seasons in animals. Structure Photoreceptor proteins typically consist of a protein moiety and a non protein photopigment that reacts to light via photoisomerization or photoreduction , thus initiating a change of the receptor protein which triggers a signal transduction cascade. Pigments found in photoreceptors include retinal retinylidene protein s, for example rhodopsin in animals , Flavin group flavin flavoprotein s, for example cryptochrome in plants and animals and Bilin biochemistry bilin biliprotein s, for example phytochrome in plants . Photoreceptors in animals Also see Photoreceptor cell Melanopsin in vertebrate retina, mediates pupillary reflex, involved in regulation of circadian rhythms Photopsin in vertebrate retina, reception of various colors of light Rhodopsin in vertebrate retina, green blue light reception Photoreceptors in plants Cryptochrome in plants, blue light reception Phototropin in plants, mediates phototropism Phytochrome in plants, red and far red light reception In plant seeds, the photoreceptor phytochrome is responsible for the process termed photomorphogenesis. This occurs when a seed initially situated in an environment of complete darkness is exposed to light. After a brief exposure to light, particularly the wavelengths within the red and far red lights of the electromanetic spectr ... more details
and derivatives is the photoisomerization of trans isomer trans and Cis trans isomerism cis isomers ... plays a direct role in the series of the photoisomerization behavior. However, the latest research ... isomerization pathway has been proposed by Diau, ref A New Trans to Cis Photoisomerization Mechanism ... crystal mesogen s in many materials. The large geometry change associated with azobenzene photoisomerization ... more details
chembox verifiedrevid 399696324 ImageFile Bromoiodomethane.png ImageSize 120px IUPACName Bromoiodomethane OtherNames Bromo iodo methane, Bromomethyl iodide, Iodobromomethane Section1 Chembox Identifiers ChemSpiderID Ref chemspidercite correct chemspider ChemSpiderID 61690 SMILES1 BrCI StdInChI Ref stdinchicite correct chemspider StdInChI 1S CH2BrI c2 1 3 h1H2 StdInChIKey Ref stdinchicite correct chemspider StdInChIKey TUDWMIUPYRKEFN UHFFFAOYSA N CASNo 557 68 6 PubChem 68407 SMILES C Br I InChI 1 CH2BrI c2 1 3 h1H2 Section2 Chembox Properties Formula CH sub 2 sub BrI MolarMass 220.84 g mol Appearance Liquid Density 2.926 g cm sup 3 sup at 17 C MeltingPt 1 C BoilingPt 139.5 C Solubility Section3 Chembox Hazards EUClass Irritant Xi MainHazards FlashPt Autoignition RPhrases R37 38 R41 SPhrases S26 S36 39 Bromoiodomethane is a liquid mixed halomethane very soluble in chloroform . Its critical point is at 367.85 C and 6.3 MPa and refractive index is 1.6382 20 C, D . References cite journal author Tarnovsky A. N., Wall M., Gustafsson M., Lascoux N., Sundstr m V., kesson E. date March 2002 title Ultrafast Study of the Photodissociation of Bromoiodomethane in Acetonitrile upon 266 nm Excitation journal J. Phys. Chem. A volume 106 issue 25 pages 5999 6005 7 pmid doi 10.1021 jp014306j url http pubs.acs.org cgi bin abstract.cgi jpcafh 2002 106 i25 abs jp014306j.html accessdate 2007 06 29 cite journal author Liu Y. J., Ajitha D., Krogh J. W., Tarnovsky A. N., Lindh R. date December 2005 title Spin Orbit Ab Initio Investigation of the Photolysis of Bromoiodomethane journal ChemPhysChem volume 7 issue 4 pages 955 963 9 pmid 16596616 doi 10.1002 cphc.200500654 url http www3.interscience.wiley.com cgi bin abstract 112580100 ABSTRACT?CRETRY 1&SRETRY 0 accessdate 2007 06 29 cite journal author Zheng, X. Phillips, D. L. date August 2000 title Photoisomerization reaction of CH2BrI following A band and B band photoexcitation in the solution phase Transient resonance Raman observation of ... more details
Retinylidene proteins are a family of proteins that use retinal as chromophore for light reception. Proteins of this family are also called opsin s. They are the molecular basis for a variety of light sensing systems from phototaxis in flagellate s to eyesight in animal s. Structure All rhodopsins consist of two building blocks, a protein moiety and a reversibly covalent ly bound non protein Cofactor biochemistry cofactor , retinal retinaldehyde . The protein structure of rhodopsin consists of a bundle of seven Transmembrane helix transmembrane helices that form an internal pocket binding the photoreactive chromophore. They form a superfamily with other membrane bound receptors containing seven transmembrane domains, for example odor and chemokine receptors. ref name Sakmar cite journal author Sakmar T title Structure of rhodopsin and the superfamily of seven helical receptors the same and not the same journal Curr Opin Cell Biol volume 14 issue 2 pages 189 95 year 2002 pmid 11891118 doi 10.1016 S0955 0674 02 00306 X ref Mechanism of light reception Instead of being activated by binding chemical ligand s like their relatives, rhodopsins contain retinal which changes conformation in reaction to light via photoisomerization and thus are activated by light. The retinal molecule can take on several different Cis trans isomerism cis trans isomeric forms, such as all trans , 11 cis and 13 cis . Photoisomerization light dependent isomerization of retinal from cis to trans or vice versa induces a conformational change in the receptor protein. This change acts as a molecular switch to activate a signal transduction mechanism within the cell. Depending on the type of rhodopsin, it either opens an ion channel for example in bacteria or activates an associated G protein and triggers a second messenger cascade for example in animal eyes . Types of rhodopsins Retinylidene proteins or rhodopsins are present in many species from bacteria to algae and animals. They can be divided in ... more details
stimuli. For example, photoisomerization behaviors of some complexes can be switched by oxidation ..., magnetic interaction of metal sites, or stability of metal to ligand coordination by photoisomerization ... thumb right 400px Azobenzene photoisomerization. The photochromic trans cis isomerization of azobenzene ... more details
, for instance, with maleic acid and with azobenzene often by photoisomerization . Another ... Photoisomerization An Integrative Guided Inquiry Experiment Elyse Bernard, Philip Britz McKibbin ... isomerization.png 400px Resveratrol photoisomerization Aldose ketose isomerization Aldose ketose ... more details
endothermic reaction endothermic photoisomerization of the trans isomer trans P , P isomer ... rotation is blocked. A second photoisomerization converts P , P cis 3 into M , M trans 4 , again ... more details
The di pi methane rearrangement is a Mechanistic Organic Photochemistry photochemical reaction of a molecular entity comprising two pi bond systems , separated by a saturated carbo n atom a 1,4 diene or an allyl substituted aromatic analog , to form an ene or aryl substituted cyclopropane . The rearrangement reaction formally amounts to a 1,2 shift of one ene group in the diene or the aryl group in the allyl aromatic analog and bond formation between the lateral carbons of the non migrating moiety. ref GoldBookRef file D01745 title di &pi methane rearrangement ref ref cite journal author title Synthetic Aspects of the Di methane Rearrangement doi 10.1021 cr910109c pmid 11848853 year 1996 last1 Zimmerman first1 Howard E. last2 Armesto first2 Diego journal Chemical Reviews volume 96 issue 8 pages 3065 3112 ref Image di pi methane.png center 200px Di pi methane rearrangement Discovery & mechanism This rearrangement was originally encountered in the photolysis of barrelene to give semibullvalene . ref Zimmerman, H. E. Grunewald, G. L. 1966 . The Chemistry of Barrelene. III. A Unique Photoisomerization to Semibullvalene . J. Am. Chem. Soc. 88 1 183 184. doi 10.1021 ja00953a045 ref Once the mechanism was recognized as general by Howard Zimmerman Zimmerman in 1967, it was clear that the structural requirement was having two pi groups attached to an sp3 hybridized carbon, and then a variety of further examples was obtained. One was the photolysis of the Mariano Compound , 3,3 methyl 1,1,5,5 tetraphenyl 1,4 pentadiene. ref cite journal author title doi 10.1021 ja00991a064 year 1967 last1 Zimmerman first1 Howard E. last2 Binkley first2 Roger W. last3 Givens first3 Richard S. last4 Sherwin first4 Maynard A. journal Journal of the American Chemical Society volume 89 pages 3932 issue 15 ref ref name Mariano The Di pi Methane Rearrangement. Interaction of Electronically Excited Vinyl Chromophores. Zimmerman, H. E. Mariano, P. S. J. Am. Chem. Soc., 1969, 91, 1718 1727. ref ref ... more details
crystallography on rhodopsin crystals. The photoisomerization dynamics has been investigated with time ... matthews rhodopsin.html Photoisomerization of rhodopsin , animation. http www.chm.bris.ac.uk ... more details
Image visual cycle v2.png 400px thumb right The Visual Cycle. h sub v sub Incident photon Visual phototransduction is a process by which light is converted into electrical signal s in the rod cell s, cone cell s and photosensitive ganglion cell s of the retina of the human eye eye . The visual cycle is the biological conversion of a photon into an electrical signal in the retina . This process occurs via G protein coupled receptor s called opsin s which contain the chromophore 11 cis retinal . 11 cis retinal is covalently linked to the opsin receptor via a Schiff base forming a retinylidene protein . When struck by a photon , 11 cis retinal undergoes photoisomerization to all trans retinal which changes the conformation of the opsin GPCR leading to signal transduction cascades which causes closure of a cyclic GM gated cation channel, and hyperpolarization of the photoreceptor cell. Following isomerization and release from the opsin protein , all trans retinal is reduced to all trans retinol and travels back to the retinal pigment epithelium to be recharged . It is first ester esterified by LRAT lecithin retinol acyltransferase LRAT and then converted to 11 cis retinol by the isomerohydrolase RPE65 . The isomerase activity of RPE65 has been shown, but it is still uncertain whether it also acts as a hydrolase. Finally, it is oxidized to 11 cis retinal before traveling back to the rod cell rod outer segment where it can again be conjugated to an opsin to form a new, functional visual pigment rhodopsin . Photoreceptors The photoreceptor cell s involved in vision are the Rod cell rods and cone cell cones . These cells contain a chromophore 11 cis retinal , the aldehyde of vitamin a Vitamin A1 and light absorbing portion bound to a cell membrane protein, opsin . Rods deal with low light level and do not mediate color vision. Cones, on the other hand, can code the color of an image through comparison of the outputs of the three different types of cones. Each co ... more details
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