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Phytoene
Phytoene () is a 40-carbon intermediate in the biosynthesis of carotenoids. The synthesis of phytoene is the first committed step in the synthesis of carotenoids in plants. Phytoene is produced from two molecules of geranylgeranyl pyrophosphate (GGPP) by the action of the enzyme phytoene synthase. The two GGPP molecules are condensed together followed by removal of diphosphate and proton shift leading to the formation of phytoene. Dietary phytoene and phytofluene are found in a number of human tissues including the liver, lung, breast, prostate, colon, and skin. Accumulation of these carotenoids in the skin may protect the skin by several mechanisms: acting as UV absorbers, as antioxidants, and as anti-inflammatory agents. Structure Phytoene is a symmetric molecule containing three conjugated double bonds. Phytoene has a UV-Vis absorption spectrum ''typical'' for a triply conjugated system with its main absorption maximum in the UVB range at 286 nm and with '' ε1% of 915 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytoene Synthase
Phytoene synthase (, ''prephytoene-diphosphate synthase'', ''15-cis-phytoene synthase'', ''PSase'', ''geranylgeranyl-diphosphate geranylgeranyltransferase'') is a transferase enzyme involved in the biosynthesis of carotenoids. It catalyzes the conversion of geranylgeranyl pyrophosphate to phytoene. This enzyme catalyses the following chemical reaction : 2 geranylgeranyl diphosphate \rightleftharpoons 15-cis-phytoene + 2 diphosphate (overall reaction) :(1a) 2 geranylgeranyl diphosphate \rightleftharpoons diphosphate + prephytoene diphosphate :(1b) prephytoene diphosphate \rightleftharpoons 15-cis-phytoene + diphosphate This enzyme requires Mn2+ for activity. It belongs to squalene/phytoene synthase family The squalene/phytoene synthase family represents proteins that catalyze the head-to-head condensation of C15 and C20 prenyl units (i.e. farnesyl diphosphate and genranylgeranyl diphosphate). This enzymatic step constitutes part of steroid and c ... of proteins. Reference ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carotenoid
Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic compound, organic pigments that are produced by plants and algae, as well as several bacteria, and Fungus, fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, maize, corn, tomatoes, Domestic Canary, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Carotenoids can be produced from Lipid, fats and other basic organic metabolic building blocks by all these organisms. It is also produced by Endosymbiont, endosymbiotic bacteria in Whitefly, whiteflies. Carotenoids from the diet are stored in the fatty tissues of animals, and exclusively Carnivore, carnivorous animals obtain the compounds from animal fat. In the human diet, Small intestine#Absorption, absorption of carotenoids is improved when consumed with fat in a meal. Cooking carotenoid-containing vegetables in oil and shredding the vegetable both increase carotenoid bioavailability. There are over 1,100 known c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carotenoids
Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, corn, tomatoes, canaries, flamingos, salmon, lobster, shrimp, and daffodils. Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms. It is also produced by endosymbiotic bacteria in whiteflies. Carotenoids from the diet are stored in the fatty tissues of animals, and exclusively carnivorous animals obtain the compounds from animal fat. In the human diet, absorption of carotenoids is improved when consumed with fat in a meal. Cooking carotenoid-containing vegetables in oil and shredding the vegetable both increase carotenoid bioavailability. There are over 1,100 known carotenoids which can be further categorized into two classes, xanthophylls (which contain oxygen) and carote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phytofluene
Phytofluene is a colorless carotenoid found naturally in tomatoes and other vegetables. It is the second product of carotenoid biosynthesis. It is formed from phytoene in a desaturation reaction leading to the formation of five conjugated double bonds. In the following step, addition of carbon-carbon conjugated double bonds leads to the formation of z-carotene and appearance of visible color. Phytofluene has an absorption spectra in the UVA range, with maximal absorption at 348 nm and with ε1% of 1557. Analysis of several fruits and vegetables showed that phytoene and phytofluene are found in majority of fruits and vegetables. In contrast to all other carotenoids, phytoene Phytoene () is a 40-carbon intermediate in the biosynthesis of carotenoids. The synthesis of phytoene is the first committed step in the synthesis of carotenoids in plants. Phytoene is produced from two molecules of geranylgeranyl pyrophosphate (G ... and phytofluene, the first carotenoid precursors i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geranylgeranyl Pyrophosphate
Geranylgeranyl pyrophosphate is an intermediate in the biosynthesis of diterpenes and diterpenoids. It is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls. It is also a precursor to geranylgeranylated proteins, which is its primary use in human cells. It is formed from farnesyl pyrophosphate by the addition of an isoprene unit from isopentenyl pyrophosphate. In ''Drosophila'', geranylgeranyl pyrophosphate is synthesised by HMG-CoA encoded by the Columbus gene. Geranylgeranyl pyrophosphate is utilised as a chemoattractant for migrating germ cells that have traversed the midgut epithelia. The attractant signal is produced at the gonadal precursors, directing the germ cells to these sites, where they will differentiate into eggs and spermatozoa (sperm). Related compounds * Farnesyl pyrophosphate * Geranylgeraniol * Geranyl pyrophosphate Geranyl pyrophosphate (GPP), also known as geranyl diphosphate (GDP), is the pyrophosphate ester of the terpenoi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjugated Double Bond
In theoretical chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases Chemical stability, stability. It is Resonance (chemistry), conventionally represented as having alternating single and multiple covalent bond, bonds. Lone pairs, radical (chemistry), radicals or carbenium ions may be part of the system, which may be Cyclic molecule, cyclic, acyclic, Linear molecular geometry, linear or mixed. The term "conjugated" was coined in 1899 by the German chemist Johannes Thiele (chemist), Johannes Thiele. Conjugation is the orbital overlap, overlap of one p-orbital with another across an adjacent Sigma bond, σ bond (in transition metals, d-orbitals can be involved). A conjugated system has a region of overlapping p-orbitals, bridging the interjacent locations that simple diagrams illustrate as not having a π bond. They allow a delocalization of pi electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basil Weedon
Professor Basil Charles Leicester Weedon CBE, FRS (18 July 1923 – 10 October 2003) was an organic chemist and university administrator. Using nuclear magnetic resonance spectroscopy, he was the first to map the structures of carotenoid pigments, including astaxanthin, rubixanthin and canthaxanthin. Personal life Weedon was born in Wimbledon, his father was a dentist and his mother came from a family of prosperous jewellers. His parents separated when he was nine years old and he remained living with his father, within a few years he had lost all contact with his mother and his younger sister. During World War II, he was evacuated to a farm near Guildford. His wife, Barbara Dawe, served in the Women's Royal Navy Service during World War II, whilst working there she met Basil's cousin and later Basil. They married in 1959 and had two children, Sarah and Matthew. Weedon suffered from Parkinson's disease in his later years. Academic life He attended Wandsworth Grammar School ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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