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Homocitrate
Homocitric acid is an organic compound with the formula HOC(CO2H)(CH2CO2H)(C2H4CO2H). This tricarboxylic acid occurs naturally as a component of the iron-molybdenum cofactor of certain nitrogenase proteins. Biochemists often refer to this cofactor as homocitrate, which is the conjugate bases that predominate in neutral aqueous solutions of this species. The molecule is related to citric acid by the addition of one methylene unit, hence the prefix "homo." Unlike citric acid, homocitric acid is chiral. The acid exists in equilibrium with the lactone. : See also * Homoisocitric acid Homoisocitric acid is an isomer of homocitric acid in which the hydroxyl is on the 2 position. It is an intermediate in the α-aminoadipate pathway of lysine biosynthesis where it is produced by homocitrate synthase and is a substrate for homo ... References Alpha hydroxy acids Chelating agents Tricarboxylic acids {{acid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron-molybdenum Cofactor
FeMoco ( cofactor) or M-cluster is the primary cofactor of nitrogenase. Nitrogenase is the enzyme that catalyzes the conversion of atmospheric nitrogen molecules N2 into ammonia (NH3) through the process known as nitrogen fixation. Because it contains iron and molybdenum, the cofactor is called FeMoco. Its stoichiometry is Fe7MoS9C. Structure The FeMo cofactor is a cluster with composition Fe7MoS9C. This cluster can be viewed as two subunits composed of one Fe4S3 ( iron(III) sulfide) cluster and one MoFe3S3 cluster. The two clusters are linked by three sulfide ligands and a bridging carbon atom. The unique iron (Fe) is anchored to the protein by a cysteine. It is also bound to three sulfides, resulting in tetrahedral molecular geometry. The additional six Fe centers in the cluster are each bonded to three sulfides. These six internal Fe centers define a trigonal prismatic arrangement around a central carbide center. The molybdenum is attached to three sulfides and is anchored t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homocitrate2
Homocitric acid is an organic compound with the formula HOC(CO2H)(CH2CO2H)(C2H4CO2H). This tricarboxylic acid occurs naturally as a component of the iron-molybdenum cofactor of certain nitrogenase proteins. Biochemists often refer to this cofactor as homocitrate, which is the conjugate bases that predominate in neutral aqueous solutions of this species. The molecule is related to citric acid by the addition of one methylene unit, hence the prefix "homo." Unlike citric acid, homocitric acid is chiral. The acid exists in equilibrium with the lactone. : See also * Homoisocitric acid Homoisocitric acid is an isomer of homocitric acid in which the hydroxyl is on the 2 position. It is an intermediate in the α-aminoadipate pathway of lysine biosynthesis where it is produced by homocitrate synthase and is a substrate for homo ... References Alpha hydroxy acids Chelating agents Tricarboxylic acids {{acid-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homoisocitric Acid
Homoisocitric acid is an isomer of homocitric acid in which the hydroxyl is on the 2 position. It is an intermediate in the α-aminoadipate pathway of lysine biosynthesis where it is produced by homocitrate synthase and is a substrate for homoaconitase. Homoisocitrate is an anion, salt, or ester of homoisocitric acid. See also * Homoaconitic acid * Adipic acid Adipic acid or hexanedioic acid is the organic compound with the formula C6H10O4. It a white crystalline powder at standard temperature and pressure. From an industrial perspective, it is the most important dicarboxylic acid at about 2.5 billion ... References {{Reflist Tricarboxylic acids Alpha hydroxy acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-containing compounds such as alkanes (e.g. methane ) and its derivatives are universally considered organic, but many others are sometimes considered inorganic, such as certain compounds of carbon with nitrogen and oxygen (e.g. cyanide ion , hydrogen cyanide , chloroformic acid , carbon dioxide , and carbonate ion ). Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, and even ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricarboxylic Acid
A tricarboxylic acid is an organic carboxylic acid that contain three carboxyl functional groups (−COOH). A well-known example is citric acid. Promient examples Some prominent substituted tricarboxylic acids Citric acid, is used in the citric acid cyclealso known as the ''tricarboxylic acid'' (''TCA'') ''cycle'' or ''Krebs cycle''which is fundamental to all aerobic organisms. Nitrilotriacetic acid (NTA) is a chelating agent for Ca2+, Co2+, Cu2+, and Fe3+. See also * Citric acid cycle (tricarboxylic acid cycle) * Dicarboxylic acid In organic chemistry, a dicarboxylic acid is an organic compound containing two carboxyl groups (). The general molecular formula for dicarboxylic acids can be written as , where R can be aliphatic or aromatic.Boy Cornils, Peter Lappe "Dicarbox ... * Mellitic acid References Literature *{{cite journal , title = The Tricarboxylic Acid Cycle, an Ancient Metabolic Network with a Novel Twist. , author = Ryan J. Mailloux, Robin Bériaul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogenase
Nitrogenases are enzymes () that are produced by certain bacteria, such as cyanobacteria (blue-green bacteria) and rhizobacteria. These enzymes are responsible for the reduction of nitrogen (N2) to ammonia (NH3). Nitrogenases are the only family of enzymes known to catalyze this reaction, which is a step in the process of nitrogen fixation. Nitrogen fixation is required for all forms of life, with nitrogen being essential for the biosynthesis of molecules (nucleotides, amino acids) that create plants, animals and other organisms. They are encoded by the Nif genes or homologs. They are related to protochlorophyllide reductase. Classification and structure Although the equilibrium formation of ammonia from molecular hydrogen and nitrogen has an overall negative enthalpy of reaction ( \Delta H^ = -45.2 \ \mathrm \, \mathrm \; \mathrm ), the activation energy is very high ( E_\mathrm = 230-420 \ \mathrm \, \mathrm ). Nitrogenase acts as a catalyst, reducing this energy barrie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citric Acid
Citric acid is an organic compound with the formula . It is a Transparency and translucency, colorless Weak acid, weak organic acid. It occurs naturally in Citrus, citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. More than two million tons of citric acid Commodity chemicals, are manufactured every year. It is used widely as acidifier, flavoring, preservative, and chelating agent. A citrate is a derivative of citric acid; that is, the salt (chemistry), salts, esters, and the polyatomic ion, polyatomic anion found in solutions and salts of citric acid. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate. When citrate anion, trianion is part of a salt, the formula of the citrate trianion is written as or . Natural occurrence and industrial production Citric acid occurs in a variety of fruits and vegetables, most notably Citrus, citrus fruits. Lemons and Lime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylene Bridge
In chemistry, a methylene bridge is part of a molecule with formula . The carbon atom is connected by single bonds to two other distinct atoms in the rest of the molecule. A methylene bridge is often called a methylene group or simply methylene, as in "methylene chloride" (dichloromethane ). As a bridge in other compounds, for example in cyclic compounds, it is given the name methano. However, the term methylidene group (not to be confused with the term methylene group, nor the carbene Methylene (compound), methylidene) properly applies to the group when it is connected to the rest of the molecule by a double bond (), giving it chemical properties very distinct from those of a bridging group. Organic chemistry It is the repeating unit in the skeleton of the unbranched alkanes. Polyethylene also can be called polymethylene. Compounds possessing a methylene bridge located between two electron withdrawing groups (such as Nitro compound, nitro, carbonyl or nitrile groups) are som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chirality (chemistry)
In chemistry, a molecule or ion is called chiral () if it cannot be superposed on its mirror image by any combination of rotation (geometry), rotations, translation (geometry), translations, and some Conformational isomerism, conformational changes. This geometric property is called chirality (). The terms are derived from Ancient Greek (''cheir'') 'hand'; which is the canonical example of an object with this property. A chiral molecule or ion exists in two stereoisomers that are mirror images of each other, called enantiomers; they are often distinguished as either "right-handed" or "left-handed" by their absolute configuration or some other criterion. The two enantiomers have the same chemical properties, except when reacting with other chiral compounds. They also have the same physics, physical properties, except that they often have opposite optical activity, optical activities. A homogeneous mixture of the two enantiomers in equal parts is said to be racemic mixture, racem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lactone
Lactones are cyclic carboxylic esters. They are derived from the corresponding hydroxycarboxylic acids by esterification. They can be saturated or unsaturated. Lactones are formed by lactonization, the intramolecular esterification of the corresponding hydroxycarboxylic acids. Nomenclature Greek alphabet#Letters, Greek prefixes in alphabetical order indicate ring size. Lactones are usually named according to the precursor acid molecule (''aceto'' = 2 carbon atoms, ''propio'' = 3, ''butyro'' = 4, ''valero'' = 5, ''capro'' = 6, etc.), with a ''-lactone'' suffix and a Greek letter prefix that specifies the number of carbon atoms in the heterocycle — that is, the distance between the relevant -OH and the -COOH groups along said backbone. The first carbon atom after the carbon in the -COOH group on the parent compound is labelled α, the second will be labeled β, and so forth. Therefore, the prefixes also indicate the size of the lactone ring: α-lactone = 3-membered ring, β-lac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Hydroxy Acids
Alpha hydroxy carboxylic acids, or α-hydroxy carboxylic acids (AHAs), are a group of carboxylic acids featuring a hydroxy group located ''one'' carbon atom away from the acid group. This structural aspect distinguishes them from beta hydroxy acids, where the functional groups are separated by ''two'' carbon atoms. Notable AHAs include glycolic acid, lactic acid, mandelic acid, and citric acid. α-Hydroxy acids are Strong acids, stronger acids compared to their non-alpha hydroxy counterparts, a property enhanced by internal hydrogen bonding. AHAs serve a dual purpose: industrially, they are utilized as additives in animal feed and as precursors for polymer synthesis. In cosmetics, they are commonly used for their ability to chemically exfoliate the skin. Occurrence Aldonic acids, a type of sugar acid, are a class of naturally occurring hydroxycarboxylic acids. They have the general chemical formula, HO2C(CHOH)''n''CH2OH. Gluconic acid, a particularly common aldonic acid, the oxidi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chelating Agents
Chelation () is a type of bonding of ions and their molecules to metal ions. It involves the formation or presence of two or more separate coordinate bonds between a polydentate (multiple bonded) ligand and a single central metal atom. These ligands are called chelants, chelators, chelating agents, or sequestering agents. They are usually organic compounds, but this is not a necessity. The word ''chelation'' is derived from Greek χηλή, ''chēlē'', meaning "claw"; the ligands lie around the central atom like the claws of a crab. The term ''chelate'' () was first applied in 1920 by Sir Gilbert T. Morgan and H. D. K. Drew, who stated: "The adjective chelate, derived from the great claw or ''chele'' (Greek) of the crab or other crustaceans, is suggested for the caliperlike groups which function as two associating units and fasten to the central atom so as to produce heterocyclic rings." Chelation is useful in applications such as providing nutritional supplements, in chela ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
