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Aconitase
Aconitase (aconitate hydratase; ) is an enzyme that catalyses the stereochemistry, stereo-specific isomerization of citrate to isocitrate via ''cis''-aconitate in the tricarboxylic acid cycle, a non-redox-active process. Image:Citrate wpmp.png, Image:Aconitic acid.svg, Image:isocitric acid.svg, Structure Aconitase has two slightly different structures, depending on whether it is activated or inactivated. In the inactive form, its structure is divided into four domains. Counting from the N-terminus, only the first three of these domains are involved in close interactions with the [3Fe-4S] cluster, but the active site consists of residues from all four domains, including the larger C-terminal domain. The Fe-S cluster and a anion also reside in the active site. When the enzyme is activated, it gains an additional iron atom, creating a [4Fe-4S] cluster. However, the structure of the rest of the enzyme is nearly unchanged; the conserved atoms between the two forms are in es ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Iron-responsive Element-binding Protein
The iron-responsive element-binding proteins, also known as IRE-BP, IRBP, IRP and IFR , bind to iron-responsive elements (IREs) in the regulation of human iron metabolism. Function ACO1, or IRP1, is a bifunctional protein that functions as an iron-responsive element (IRE)-binding protein involved in the control of iron metabolism by binding mRNA to repress translation or degradation. It functions also as the cytoplasmic isoform of aconitase. Aconitases are iron-sulfur proteins that require a 4Fe-4S cluster for their enzymatic activity, in which they catalyze conversion of citrate to isocitrate. This structure was based on x-ray crystal diffraction. The resolution was 2.80 Å. This protein was harvested from the species ''Oryctolagus cuniculus'', more commonly known as a rabbit. This protein has a couple of conformational changes associated with it to explain the alternative functions as either mRNA regulator or as an enzyme. This information was obtained from the RCSB protein d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
3-Isopropylmalate Dehydratase
3-Isopropylmalate dehydratase () is an aconitase homologue, which catalyses the isomerisation of isopropylmalate, 2-isopropylmalate to 3-isopropylmalate, via Dehydration reaction, dehydration, in the biosynthesis of leucine. References External links * Lyases {{enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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] [Amazon] |
Fluoroacetic Acid
Fluoroacetic acid is an organofluorine compound with the chemical formula . It is a colorless solid that is noted for its relatively high toxicity. The conjugate base, fluoroacetate occurs naturally in at least 40 plants in Australia, Brazil, and Africa. It is one of only five known organofluorine-containing natural products. Toxicity Fluoroacetic acid is a harmful metabolite of some fluorine-containing drugs (median lethal dose, LD50 = 10 mg/kg in humans). The most common metabolic sources of fluoroacetic acid are fluoroamines and fluoroethers. Fluoroacetic acid can disrupt the Krebs cycle. The metabolite of fluoroacetic acid is Fluorocitric acid and is very toxic because it is not processable using aconitase in the Krebs cycle (where fluorocitrate takes place of citrate as the substrate). The enzyme is inhibited and the cycle stops working. In contrast with fluoroacetic acid, difluoroacetic acid and trifluoroacetic acid are far less toxic. Its p''K''a is 2.66, in contras ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Citrate Zoom Final
Citric acid is an organic compound with the formula . 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 acidifier, flavoring, preservative, and chelating agent. A citrate is a derivative of citric acid; that is, the salts, esters, and the 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 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 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Aconitic Acid
Aconitic acid refers to organic compounds with the formula . A white solid, it is classified as a tricarboxylic acid. The two isomers are ''cis''-aconitic acid and ''trans''-aconitic acid. The conjugate base of ''cis''-aconitic acid, ''cis''-aconitate is an intermediate in the isomerization of citrate to isocitrate in the citric acid cycle. It is acted upon by the enzyme aconitase. Aconitic acid can be synthesized by dehydration of citric acid using sulfuric acid: :(HO2CCH2)2C(OH)CO2H → HO2CCH=C(CO2H)CH2CO2H + H2O A mixture of isomers is generated in this way. Aconitic acid was originally isolated from ''Aconitum napellus'' by Swiss chemist and apothecary Jacques Peschier in 1820. It was first prepared by thermal dehydration. Like the conjugate bases of other polycarboxylic acid, acotinic acid forms a variety of coordination complexes. One example is the coordination polymer Coordination may refer to: * Coordination (linguistics), a compound grammatical construction * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Isocitric Acid
Isocitric acid is a structural isomer of citric acid. Since citric acid and isocitric acid are structural isomers, they share similar physical and chemical properties. Due to these similar properties, it is difficult to separate the isomers. Salts and esters of isocitric acid are known as isocitrates. The isocitrate anion is a substrate of the citric acid cycle. Isocitrate is formed from citrate with the help of the enzyme aconitase, and is acted upon by isocitrate dehydrogenase. Isocitric acid is commonly used as a marker to detect the authenticity and quality of fruit products, most often citrus juices. In authentic orange juice, for example, the ratio of citric acid to D-isocitric acid is usually less than 130. An isocitric acid value higher than this may be indicative of fruit juice adulteration. Isocitric acid has largely been used as a biochemical agent due to limited amounts. However, isocitric acid has been shown to have pharmaceutical and therapeutic effects. Isocitr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Aconitate
Aconitic acid refers to organic compounds with the formula . A white solid, it is classified as a tricarboxylic acid. The two isomers are ''cis''-aconitic acid and ''trans''-aconitic acid. The conjugate base of ''cis''-aconitic acid, ''cis''-aconitate is an intermediate in the isomerization of citrate to isocitrate in the citric acid cycle. It is acted upon by the enzyme aconitase. Aconitic acid can be synthesized by dehydration of citric acid using sulfuric acid: :(HO2CCH2)2C(OH)CO2H → HO2CCH=C(CO2H)CH2CO2H + H2O A mixture of isomers is generated in this way. Aconitic acid was originally isolated from ''Aconitum napellus'' by Swiss chemist and apothecary Jacques Peschier in 1820. It was first prepared by thermal dehydration. Like the conjugate bases of other polycarboxylic acid, acotinic acid forms a variety of coordination complexes. One example is the coordination polymer Coordination may refer to: * Coordination (linguistics), a compound grammatical construction * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Isocitrate
Isocitric acid is a structural isomer of citric acid. Since citric acid and isocitric acid are structural isomers, they share similar physical and chemical properties. Due to these similar properties, it is difficult to separate the isomers. Salts and esters of isocitric acid are known as isocitrates. The isocitrate anion is a substrate of the citric acid cycle. Isocitrate is formed from citrate with the help of the enzyme aconitase, and is acted upon by isocitrate dehydrogenase. Isocitric acid is commonly used as a marker to detect the authenticity and quality of fruit products, most often citrus juices. In authentic orange juice, for example, the ratio of citric acid to D-isocitric acid is usually less than 130. An isocitric acid value higher than this may be indicative of fruit juice adulteration. Isocitric acid has largely been used as a biochemical agent due to limited amounts. However, isocitric acid has been shown to have pharmaceutical and therapeutic effects. Isocitric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Citrate
Citric acid is an organic compound with the formula . It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, a ..., 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 for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Oxaloacetate
Oxaloacetic acid (also known as oxalacetic acid or OAA) is a crystalline organic compound with the chemical formula HO2CC(O)CH2CO2H. Oxaloacetic acid, in the form of its conjugate base oxaloacetate, is a metabolic intermediate in many processes that occur in animals. It takes part in gluconeogenesis, the urea cycle, the glyoxylate cycle, amino acid synthesis, fatty acid synthesis and the citric acid cycle. Properties Oxaloacetic acid undergoes successive deprotonations to give the dianion: :HO2CC(O)CH2CO2H −O2CC(O)CH2CO2H + H+, pKa = 2.22 :−O2CC(O)CH2CO2H −O2CC(O)CH2CO2− + H+, pKa = 3.89 At high pH, the enolizable proton is ionized: :−O2CC(O)CH2CO2− −O2CC(O−)CHCO2− + H+, pKa = 13.03 The enol forms of oxaloacetic acid are particularly stable. Keto-enol tautomerization is catalyzed by the enzyme oxaloacetate tautomerase. ''trans''-Enol-oxaloacetate also appears when tartrate is the substrate for fumarase. Biosynthesis Oxaloacetate forms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Acetyl CoA
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production. Coenzyme A (CoASH or CoA) consists of a β-mercaptoethylamine group linked to pantothenic acid (vitamin B5) through an amide linkage and 3'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol). CoA is acetylated to acetyl-CoA by the breakdown of carbohydrates through glycolysis and by the breakdown of fatty acids through β-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is oxidized to carbon dioxide and wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
