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Tetrahymanol
Tetrahymanol is a gammacerane-type membrane lipid first found in the marine ciliate ''Tetrahymena, Tetrahymena pyriformis''. It was later found in other ciliates, Fungus, fungi, ferns, and bacteria. After diagenesis, being deposited in sediments that compress into sedimentary rocks over millions of years, tetrahymanol is dehydroxylated into gammacerane. Gammacerane has been interpreted as a proxy for ancient water column stratification. Chemistry Structure Tetrahymanol is a pentacyclic Triterpene, triterpenoid molecule. The triterpenoids are a class of molecules found in both bacteria and eukaryotes, which largely make Hopanoids, hopanols and sterols, respectively. The structures of these three classes of molecules are shown below. Cholesterol and diploptene are used as model sterol and hopanol structures, respectively. While diploptene and tetrahymanol broadly have similar structures, the fifth ring on tetrahymanol is a cyclohexane rather than a cyclopentane. All three of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hopanoids
Hopanoids are a diverse subclass of triterpenoids with the same hydrocarbon skeleton as the compound hopane. This group of pentacyclic molecules therefore refers to simple hopenes, hopanols and hopanes, but also to extensively functionalized derivatives such as bacteriohopanepolyols (BHPs) and hopanoids covalently attached to lipid A. The first known hopanoid, hydroxyhopanone, was isolated by two chemists at The National Gallery, London working on the chemistry of dammar gum, a natural resin used as a varnish for paintings. While hopanoids are often assumed to be made only in bacteria, their name actually comes from the abundance of hopanoid compounds in the resin of plants from the genus ''Hopea''. In turn, this genus is named after John Hope, the first Regius Keeper of the Royal Botanic Garden, Edinburgh. Since their initial discovery in an angiosperm, hopanoids have been found in plasma membranes of bacteria, lichens, bryophytes, ferns, tropical trees and fungi. Hopanoids have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahymanol Synthase
Tetrahymanol synthase (, ''squalene tetrahymanol cyclase'') is an enzyme with systematic name ''squalene hydro-lyase (tetrahymanol forming)''. This enzyme catalyses the following chemical reaction : tetrahymanol Tetrahymanol is a gammacerane-type membrane lipid first found in the marine ciliate ''Tetrahymena, Tetrahymena pyriformis''. It was later found in other ciliates, Fungus, fungi, ferns, and bacteria. After diagenesis, being deposited in sediments t ... \rightleftharpoons squalene + H2O The reaction occurs in the reverse direction. This enzyme is isolated from Tetrahymena protozoans. References External links * {{Portal bar, Biology, border=no EC 4.2.1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gammacerane
Gammacerane is a pentacyclic triterpene compound with the formula C30H52 and five six-membered rings. Its derivatives include tetrahymanol（Gammaceran-3β-ol）and so on. After millions of years of diagenesis, these derivatives became gammacerane can be used as biomarkers in petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ... to study the origin of petroleum. See also * * Hopane and References Triterpenes {{organic-compound-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stereoisomerism
In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space. This contrasts with structural isomers, which share the same molecular formula, but the bond connections or their order differs. By definition, molecules that are stereoisomers of each other represent the same structural isomer. Enantiomers Enantiomers, also known as optical isomers, are two stereoisomers that are related to each other by a reflection: they are mirror images of each other that are non-superposable. Human hands are a macroscopic analog of this. Every stereogenic center in one has the opposite configuration in the other. Two compounds that are enantiomers of each other have the same physical properties, except for the direction in which they rotate polarized light and how they interact with different optical iso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylation
In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and the biological sciences. In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing. In vitro methylation of tissue samples is also one method for reducing certain histological staining artifacts. The reverse of methylation is demethylation. In biology In biological systems, methylation is accomplished by enzymes. Methylation can modify heavy metals, regulate gene expression, RNA processing and protein function. It has been recognized as a key process underlying epigenetics. Methanogenesis Methanogenesis, the process th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biosynthesis
Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds, or joined to form macromolecules. This process often consists of metabolic pathways. Some of these biosynthetic pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these biosynthetic pathways include the production of lipid membrane components and nucleotides. Biosynthesis is usually synonymous with anabolism. The prerequisite elements for biosynthesis include: precursor compounds, chemical energy (e.g. ATP), and catalytic enzymes which may require coenzymes (e.g.NADH, NADPH). These elements create monomers, the building blocks for macromolecules. Some important biological macromolecules include: proteins, which are composed of amino acid monomers joined via peptide bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalene-hopene Cyclase
Squalene-hopene cyclase (SHC) () or ''hopan-22-ol hydro-lyase'' is an enzyme in the terpene cyclase/mutase family. It catalyzes the interconversion of squalene into a pentacyclic triterpenes, hopene and hopanol. This enzyme catalyses the following chemical reactions. : squalene \rightleftharpoons hop-22(29)-ene : squalene + H2O \rightleftharpoons hopan-22-ol SHC is important because its products, hopanoids, are very much like sterols in eukaryotes in that they condense lipid membranes and reduce permeability. In fact, SHC and sterol-producing enzymes ( oxidosqualene cyclase) are evolutionarily related to each other. Hopanoids are inferred to provide stability in the face of high temperatures and extreme acidity due to the rigid ring structure. Indeed, up-regulation of SHC occurs in certain bacteria in the presence of hot or acidic environments. SHC is found mostly in bacteria, but some eukaryotes, such as fungi and land plants, are also known to possess the enzyme. Introduct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidosqualene Cyclase
Oxidosqualene cyclases (OSC) are enzymes involved in cyclization reactions of 2,3-oxidosqualene to form sterols or triterpenes. Introduction There are two major groups of sterol-producing OSC enzymes: * Cycloartenol synthase (CAS), found in all plants, which produces primarily cycloartenol * Lanosterol synthase (LAS), found in all animals and fungi, and occasionally in plants, which produces primarily lanosterol Sterols and triterpenes are extremely diverse classes of natural products, particularly in plants, which often contain numerous OSC enzymes with different substrate and product specificities; common examples include lupeol synthase and beta-amyrin synthase. OSC enzymes' catalytic mechanism is similar to the prokaryotic squalene-hopene cyclase. Directed evolution and protein design have been used to identify small numbers of point mutations that alter the product specificities of OSC enzymes, most notably in altering a cycloartenol synthase to produce predominantly lano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squalene
Squalene is an organic compound. It is a triterpenoid with the formula C30H50. It is a colourless oil, although impure samples appear yellow. It was originally obtained from shark liver oil (hence its name, as ''Squalus'' is a genus of sharks). All plants and animals produce squalene as a biochemical intermediate to sterol biosynthesis. An estimated 12% of bodily squalene in humans is found in Sebaceous gland, sebum. Squalene has a role in topical skin lubrication and protection. Squalene is a precursor (chemistry), precursor for synthesis of all plant and animal sterols, including cholesterol and steroid hormones in the human body. Squalene is an important ingredient in some vaccine adjuvants: The Novartis and GlaxoSmithKline adjuvants are called MF59 and AS03, respectively. Role in steroid synthesis Squalene is the biochemical precursor to steroids. The squalene conversion begins with oxidation (via squalene monooxygenase) of one of its terminal double bonds, resulting in 2,3- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terpenoid
The terpenoids, also known as isoprenoids, are a class of naturally occurring organic chemicals derived from the 5-carbon compound isoprene and its derivatives called terpenes, diterpenes, etc. While sometimes used interchangeably with "terpenes", terpenoids contain additional functional groups, usually containing oxygen. When combined with the hydrocarbon terpenes, terpenoids comprise about 80,000 compounds. They are the largest class of plant secondary metabolites, representing about 60% of known natural products. Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists. Plant terpenoids are used for their aromatic qualities and play a role in traditional herbal remedies. Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves, and ginger, the yellow color in sunflowers, and the red color in tomatoes. Well-known terpenoids include citral, menthol, camphor, salvinorin A in the plant '' Salvia di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Maturity
In petroleum geology, the maturity of a rock is a measure of its state in terms of hydrocarbon generation. Maturity is established using a combination of geochemical and basin modelling techniques. Rocks with high total organic carbon, (termed source rocks), will alter under increasing temperature such that the organic molecules slowly mature into hydrocarbons (see diagenesis). Source rocks are therefore broadly categorised as ''immature'' (no hydrocarbon generation), ''sub-mature'' (limited hydrocarbon generation), ''mature'' (extensive hydrocarbon generation) and ''overmature'' (most hydrocarbons have been generated). The maturity of a source rock can also be used as an indicator of its hydrocarbon ''potential''. That is, if a rock is sub-mature, then it has a much higher potential to generate further hydrocarbons than one that is overmature. See also * Van Krevelen diagram Van Krevelen diagrams are graphical plots developed by Dirk Willem van Krevelen (chemist and professo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
