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Mesaconic Acid
Mesaconic acid is one of several isomeric carboxylic acids obtained from citric acid. It is a colorless solid. Synthesis and reactions It is prepared from citric acid, which is first converted to itaconic anhydride by dehydration and decarboxylation. Itaconic acid anhydride is isomerized to citraconic anhydride, which is hydrolyzed and the resulting acid further isomerized under acid-catalysis to give mesaconic acid. Hydration of mesaconic acid, a conversion catalyzed by mesaconyl-C4-CoA hydratase, gives citramalic acid. History This acid was studied for the first time by Jacobus H. van 't Hoff in 1874. It was later shown to be produced by ''Clostridium tetanomorphum''. Further studies showed that this organic compound is involved in the biosynthesis of vitamin B12. It is a competitive inhibitor of fumarate reduction. The compound has been considered as a renewable precursor to the commodity chemical methacrylic acid Methacrylic acid, abbreviated MAA, is an organic compoun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isomer
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties. Two main forms of isomerism are structural or constitutional isomerism, in which ''bonds'' between the atoms differ; and stereoisomerism or spatial isomerism, in which the bonds are the same but the ''relative positions'' of the atoms differ. Isomeric relationships form a hierarchy. Two chemicals might be the same constitutional isomer, but upon deeper analysis be stereoisomers of each other. Two molecules that are the same stereoisomer as each other might be in different conformational forms or be different isotopologues. The depth of analysis depends on the field of study or the chemical and physical properties of interest. The English word "isomer" () is a back-for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboxylic Acid
In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an R-group. The general formula of a carboxylic acid is or , with R referring to the alkyl, alkenyl, aryl, or other group. Carboxylic acids occur widely. Important examples include the amino acids and fatty acids. Deprotonation of a carboxylic acid gives a carboxylate anion. Examples and nomenclature Carboxylic acids are commonly identified by their trivial names. They at oftentimes have the suffix ''-ic acid''. IUPAC-recommended names also exist; in this system, carboxylic acids have an ''-oic acid'' suffix. For example, butyric acid (C3H7CO2H) is butanoic acid by IUPAC guidelines. For nomenclature of complex molecules containing a carboxylic acid, the carboxyl can be considered position one of the parent chain even if there are other substituents, such as 3-chloropropanoic acid. Alternately, it can be named as a "carboxy" or "carboxylic acid" substituent on another ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citric Acid
Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in 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 are manufactured every year. It is used widely as an acidifier, as a flavoring, and a chelating agent. A citrate is a derivative of citric acid; that is, the salts, esters, and the polyatomic anion found in solution. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate. When part of a salt, the formula of the citrate anion is written as or . Natural occurrence and industrial production Citric acid occurs in a variety of fruits and vegetables, most notably citrus fruits. Lemons and limes have particularly high concentrations of the acid; it can constitute as much as 8% of the dry weight of these fruits (about 47 g/L in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Itaconic Acid
Itaconic acid, or methylidenesuccinic acid, is an organic compound. This dicarboxylic acid is a white solid that is soluble in water, ethanol, and acetone. Historically, itaconic acid was obtained by the distillation of citric acid, but currently it is produced by fermentation. The name ''itaconic acid'' was devised as an anagram of aconitic acid, another derivative of citric acid. Production Since the 1960s, it is produced industrially by the fermentation of carbohydrates such as glucose or molasses using fungi such as '' Aspergillus itaconicus'' or ''Aspergillus terreus''. For ''A. terreus'' the itaconate pathway is mostly elucidated. The generally accepted route for itaconate is via glycolysis, tricarboxylic acid cycle, and a decarboxylation of ''cis''-aconitate to itaconate via ''cis''-aconitate-decarboxylase. The smut fungus ''Ustilago maydis'' uses an alternative route. ''Cis''-aconitate is converted to the thermodynamically favoured ''trans''-aconitate via aconitate- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citraconic Acid
Citraconic acid is an organic compound with the formula CH3C2H(CO2H)2. It is a white solid. It is the ''cis''- isomer of mesaconic acid. It is one of the pyrocitric acids formed upon the heating of citric acid. Citraconic acid can be produced, albeit inefficiently, by oxidation of xylene and methylbutanols. The acid displays the unusual property of spontaneously forming the anhydride, which, unlike maleic anhydride, is a liquid at room temperature. In the laboratory, citraconic acid can be produced by thermal isomerization of itaconic acid anhydride to give citraconic anhydride, which can be hydrolyzed to citraconic acid. The required itaconic acid anhydride is obtained by dry distillation of citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in .... References Dicarbox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Citramalic Acid
Citramalic acid is the organic compound with the formula HO2CCH2C(CH3)(OH)CO2H. A chiral compound, it is related structurally to malic acid. Synthesis and reactions Citramalic acid is the hydrated derivative of mesaconic acid, The hydration is catalyzed by mesaconyl-C4-CoA hydratase: :HO2CCH=C(CH3)CO2H + H2O → HO2CCH2C(CH3)(OH)CO2H The same conversion can be achieved in vitro. The enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ... (S)-citramalyl-CoA lyase converts citramalyl-CoA to acetyl-CoA and pyruvate.{{cite journal , doi=10.1128/AEM.02473-10, title=Ecological Aspects of the Distribution of Different Autotrophic CO2 Fixation Pathways, year=2011, last1=Berg, first1=Ivan A., journal=Applied and Environmental Microbiology, volume=77, issue=6, pages=1925–1936, pmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin B12
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it. Vitamin B12 is the most chemically complex of all vitamins, and for humans, the only vitamin that must be sourced from animal-derived foods or from supplements. Only some archaea and bacteria can synthesize vitamin B12. Most people in developed countries get enough B12 from the consumption of meat or foods with animal sources. Foods containing vitamin B12 include meat, clams, liver, fish, poultry, eggs, and dairy products. Many breakfast cereals are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fumarate
Fumaric acid is an organic compound with the formula HO2CCH=CHCO2H. A white solid, fumaric acid occurs widely in nature. It has a fruit-like taste and has been used as a food additive. Its E number is E297. The salts and esters are known as fumarates. Fumarate can also refer to the ion (in solution). Fumaric acid is the trans isomer of butenedioic acid, while maleic acid is the cis isomer. Biosynthesis and occurrence It is produced in eukaryotic organisms from succinate in complex 2 of the electron transport chain via the enzyme succinate dehydrogenase. It is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid. In fumaric acid the carboxylic acid groups are ''trans'' (''E'') and in maleic acid they are ''cis'' (''Z''). Fumaric acid is found in fumitory (''Fumaria officinalis''), bolete mushrooms (specifically ''Boletus fomentarius var. pseudo-igniarius''), lichen, and Iceland moss. Fumarate is an intermediate in the citric acid cycle used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate (chemistry), substrate change. Oxidation is the loss of Electron, electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methacrylic Acid
Methacrylic acid, abbreviated MAA, is an organic compound. This colorless, viscous liquid is a carboxylic acid with an acrid unpleasant odor. It is soluble in warm water and miscible with most organic solvents. Methacrylic acid is produced industrially on a large scale as a precursor to its esters, especially methyl methacrylate (MMA), and to poly(methyl methacrylate) (PMMA). MAA occurs naturally in small amounts in the oil of Roman chamomile. Production In the most common route, methacrylic acid is prepared from acetone cyanohydrin, which is converted to methacrylamide sulfate using sulfuric acid. This derivative in turn is hydrolyzed to methacrylic acid, or esterified to methyl methacrylate in one step. Another route to methacrylic acid starts with isobutylene, which obtainable by dehydration of ''tert''-butanol. Isobutylene is oxidized sequentially to methacrolein and then methacrylic acid. Methacrolein for this purpose can also be obtained from formaldehyde and ethylene. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
