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3-dehydroquinate
3-Dehydroquinic acid (DHQ) is the first carbocyclic intermediate of the shikimate pathway. It is created from 3-deoxyarabinoheptulosonate 7-phosphate, a 7-carbon ulonic acid, by the enzyme DHQ synthase. The mechanism of ring closure is complex, but involves an aldol condensation at C-2 and C-7. It has the same structure as quinic acid, which is found in coffee, but the C-3 hydroxyl is oxidized to a ketone group. 3-Dehydroquinic acid undergoes five further enzymatic steps in the remainder of the shikimate pathway to chorismic acid, a precursor to tyrosine, 3-phenylalanine, tryptophan, and some vitamins, including: * Vitamin K * Pteroylmonoglutamic acid, called folate. 3-Dehydroquinate can also be a precursor to pyrroloquinoline quinone (PQQ), an alternate redox coenzyme involved in oxidative phosphorylation. Biosynthesis 3-Dehydroquinate goes through beta oxidation, similar to fatty acids. Then, this compound (6-oxo-3-dehydro-quinate) is transaminated to 6-amino ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
3-deoxyarabinoheptulosonate 7-phosphate
3-Deoxy--''arabino''-heptulosonic acid 7-phosphate (DAHP) is a 7-carbon ulonic acid. This compound is found in the shikimic acid biosynthesis pathway and is an intermediate in the production of aromatic amino acids. Phosphoenolpyruvate and erythrose-4-phosphate react to form 3-deoxy--''arabino''-heptulosonate-7-phosphate (DAHP), in a reaction catalyzed by the enzyme DAHP synthase. : DAHP is then transformed to 3-dehydroquinate (DHQ), in a reaction catalyzed by DHQ synthase. Although this reaction requires nicotinamide adenine dinucleotide (NAD) as a cofactor, the enzymic mechanism regenerates it, resulting in the net use of no NAD. : The mechanism of ring closure is complex, but involves an aldol condensation at C-2 and C-7. Metabolic engineering Metabolic engineering is the practice of optimizing genetic and regulatory processes within cells to increase the cell's production of a certain substance. These processes are chemical networks that use a series of biochem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shikimate Pathway
The shikimate pathway (shikimic acid pathway) is a seven-step metabolic pathway used by bacteria, archaea, fungi, algae, some protozoans, and plants for the biosynthesis of folates and aromatic amino acids (tryptophan, phenylalanine, and tyrosine). This pathway is not found in animal cells. The seven enzymes involved in the shikimate pathway are DAHP synthase, 3-dehydroquinate synthase, 3-dehydroquinate dehydratase, shikimate dehydrogenase, shikimate kinase, EPSP synthase, and chorismate synthase. The pathway starts with two substrates, phosphoenol pyruvate and erythrose-4-phosphate, and ends with chorismate, a substrate for the three aromatic amino acids. The fifth enzyme involved is the shikimate kinase, an enzyme that catalyzes the ATP-dependent phosphorylation of shikimate to form shikimate 3-phosphate (shown in the figure below). Shikimate 3-phosphate is then coupled with phosphoenol pyruvate to give 5-enolpyruvylshikimate-3-phosphate via the enzyme 5-enolpyruvylshikimate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shikimic Acid Pathway
The shikimate pathway (shikimic acid pathway) is a seven-step metabolic pathway used by bacteria, archaea, fungi, algae, some protozoans, and plants for the biosynthesis of folates and aromatic amino acids (tryptophan, phenylalanine, and tyrosine). This pathway is not found in animal cells. The seven enzymes involved in the shikimate pathway are DAHP synthase, 3-dehydroquinate synthase, 3-dehydroquinate dehydratase, shikimate dehydrogenase, shikimate kinase, EPSP synthase, and chorismate synthase. The pathway starts with two substrates, phosphoenol pyruvate and erythrose-4-phosphate, and ends with chorismate, a substrate for the three aromatic amino acids. The fifth enzyme involved is the shikimate kinase, an enzyme that catalyzes the ATP-dependent phosphorylation of shikimate to form shikimate 3-phosphate (shown in the figure below). Shikimate 3-phosphate is then coupled with phosphoenol pyruvate to give 5-enolpyruvylshikimate-3-phosphate via the enzyme 5-enolpyruvylshikim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteroylmonoglutamic Acid
Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and storage. Folate is required for the body to make DNA and RNA and metabolise amino acids necessary for cell division. As humans cannot make folate, it is required in the diet, making it an essential nutrient. It occurs naturally in many foods. The recommended adult daily intake of folate in the U.S. is 400 micrograms from foods or dietary supplements. Folate in the form of folic acid is used to treat anemia caused by folate deficiency. Folic acid is also used as a supplement by women during pregnancy to reduce the risk of neural tube defects (NTDs) in the baby. Low levels in early pregnancy are believed to be the cause of more than half of babies born with NTDs. More than 80 countries use either mandatory or voluntary fortificati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketones
In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bond C=O). The simplest ketone is acetone (where R and R' is methyl), with the formula . Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids (e.g., testosterone), and the solvent acetone. Nomenclature and etymology The word ''ketone'' is derived from ''Aketon'', an old German word for ''acetone''. According to the rules of IUPAC nomenclature, ketone names are derived by changing the suffix ''-ane'' of the parent alkane to ''-anone''. Typically, the position of the carbonyl group is denoted by a number, but traditional nonsystematic names are still generally used for the most important ketones, for example acetone and benzophenone. These nonsystematic names are considered ret ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Hydroxy Acids
α-Hydroxy acids, or alpha hydroxy acids (AHAs), are a class of chemical compounds that consist of a carboxylic acid with a hydroxyl group substituent on the adjacent (alpha) carbon. Prominent examples are glycolic acid, lactic acid, mandelic acid and citric acid. Although these compounds are related to the ordinary carboxylic acids and are therefore weak acids, their chemical structure allows for the formation of an internal hydrogen bond between the hydrogen at the hydroxyl group and one of the oxygen atoms of the carboxylic group. The net effect is an increase in acidity. For example, the pKa of lactic acid is 3.86, while that of the unsubstituted propionic acid is 4.87; a full pKa unit difference means that lactic acid is ten times stronger than propionic acid. Industrial applications Feed additives 2-Hydroxy-4-(methylthio)butyric acid is produced commercially as a racemic mixture to substitute for methionine in animal feed. In nature, the same compound is an intermediate in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flavin Adenine Dinucleotide
Flavin may refer to: Placename * Flavin, Aveyron, a commune in southern France Surname * Adrian Flavin (born 1979), a professional rugby player * Christopher Flavin, president of the Worldwatch Institute * Dan Flavin (1933–1996), a minimalist artist famous for using fluorescent light fixtures * Dan Flavin (politician), Louisiana politician * James Flavin (1906–1976), an American character actor * Jennifer Flavin (born 1968), a former model and wife of actor Sylvester Stallone * Martin Flavin (1883–1967), an American playwright and novelist * Martin Flavin (politician) (1841–1917), Irish Nationalist politician, Member of Parliament (MP) for Cork, 1891–1892 * Michael Joseph Flavin (1866-1944), Irish Nationalist politician, Member of Parliament (MP) for North Kerry, 1896-1918 * Mick Flavin, an Irish country singer Biochemistry * Flavin adenine dinucleotide (FAD), a redox cofactor * Flavin-containing amine oxidoreductase, a family of amine oxidases * Flavin-containing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydroalanine
Dehydroalanine (Cα,β-didehydroalanine, α,β-di-dehydroalanine, 2-aminoacrylate, or 2,3-didehydroalanine) is a dehydroamino acid. It does not exist in its free form, but it occurs naturally as a residue found in peptides of microbial origin. As an amino acid residue, it is unusual because it has an unsaturated backbone. Structure and reactivity Like most primary enamines, dehydroalanine is unstable. Dehydroalanine hydrolyze to pyruvate. ''N''-Acylated derivatives of dehydroalanine, such as peptides and related compounds, are stable. For example, methyl 2-acetamidoacrylate is the N-acetylated derivative of the ester. As a residue in a peptide, it is generated by a post translational modification. The required precursors are serine or cysteine residues, which undergo enzyme-mediated loss of water and hydrogen sulfide, respectively. Most amino acid residues are unreactive toward nucleophiles, but those containing dehydroalanine or some other dehydroamino acids are exceptions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dehydration Reaction
In chemistry, a dehydration reaction is a chemical reaction that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction. Dehydration reactions in organic chemistry Esterification The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester :RCO2H + R′OH RCO2R′ + H2O Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water. Etherification Two monosaccharides, such as glucose and fructose, can be joined together (to form saccharose) using dehydration synthesis. The new molecule, consisting of two monosaccharides, is called a disaccharide. Nitrile formation Nitriles are often prepared by dehydration of primary amides. :RC(O)NH2 → RCN + H2O Ketene formation Ketene is produced by heating acetic acid and trapping the product: :CH3CO2H → CH2=C= ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transamination
Transamination is a chemical reaction that transfers an amino group to a ketoacid to form new amino acids. This pathway is responsible for the deamination of most amino acids. This is one of the major degradation pathways which convert essential amino acids to non-essential amino acids (amino acids that can be synthesized de novo by the organism). Transamination in biochemistry is accomplished by enzymes called transaminases or aminotransferases. α-ketoglutarate acts as the predominant amino-group acceptor and produces glutamate as the new amino acid. :Aminoacid + α-ketoglutarate ↔ α-keto acid + glutamate Glutamate's amino group, in turn, is transferred to oxaloacetate in a second transamination reaction yielding aspartate. :Glutamate + oxaloacetate ↔ α-ketoglutarate + aspartate Mechanism of action Transamination catalyzed by aminotransferase occurs in two stages. In the first step, the α amino group of an amino acid is transferred to the enzyme, producing the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatty Acid
In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids (up to 70% by weight) in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and important structural components for cells. History The concept of fatty acid (''acide gras'') was introduced in 1813 by Michel Eugène Chevreul, though he initially used some variant terms: ''graisse acide'' and ''acide huileux'' ("acid fat" and "oily acid"). Types of fatty acids Fatty acids are classified in many ways: by length, by saturation vs unsaturati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
