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Phosphopantetheine
Phosphopantetheine, also known as 4'-phosphopantetheine, is a prosthetic group of several acyl carrier proteins including the acyl carrier proteins (ACP) of fatty acid synthases, ACPs of polyketide synthases, the peptidyl carrier proteins (PCP), as well as aryl carrier proteins (ArCP) of nonribosomal peptide synthetases (NRPS). It is also present in formyltetrahydrofolate dehydrogenase. Subsequent to the expression of the ''apo'' acyl carrier protein, 4'-phosphopantetheine moiety is attached to a serine residue. The coupling involves formation of a phosphodiester linkage. This coupling is mediated by acyl carrier protein synthase (ACPS), a 4'-phosphopantetheinyl transferase. Phosphopantetheine prosthetic group covalently links to the acyl group via a high energy thioester bond. The flexibility and length of the phosphopantetheine chain (approximately 2 nm) allows the covalently tethered intermediates to access spatially distinct enzyme-active sites. This accessibility ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
4'-phosphopantetheinyl Transferase
In enzymology and molecular biology, a holo- cyl-carrier-proteinsynthase (ACPS, ) is an enzyme that catalyzes the chemical reaction: :CoA- '-phosphopantetheine+ apo-acyl carrier protein \rightleftharpoons adenosine 3',5'-bisphosphate + holo-acyl carrier protein This enzyme belongs to the family of transferases, specifically those transferring non-standard substituted phosphate groups. It is also known as 4'-phosphopantetheinyl transferase after the group it transfers. Function All ACPS enzymes known so far are evolutionally related to each other in a single superfamily of proteins. It transfers a 4'-phosphopantetheine (4'-PP) moiety from coenzyme A (CoA) to an invariant serine in an acyl carrier protein (ACP), a small protein responsible for acyl group activation in fatty acid biosynthesis. This post-translational modification renders holo-ACP capable of acyl group activation via thioesterification of the cysteamine thiol of 4'-PP. This superfamily consists of two subtypes: th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Pantothenic Acid
Pantothenic acid (vitamin B5) is a B vitamin and an essential nutrient. All animals need pantothenic acid in order to synthesize coenzyme A (CoA), which is essential for cellular energy production and for the synthesis and degradation of proteins, carbohydrates, and fats. Pantothenic acid is the combination of pantoic acid and beta-Alanine, β-alanine. Its name comes from the Greek language, Greek ''pantothen'', meaning "from everywhere", because pantothenic acid, at least in small amounts, is in almost all foods. Deficiency of pantothenic acid is very rare in humans. In dietary supplements and animal feed, the form commonly used is calcium pantothenate, because chemically it is more stable, and hence makes for longer product shelf-life, than sodium pantothenate and free pantothenic acid. Definition Pantothenic acid is a water-soluble vitamin, one of the B vitamins. It is synthesized from the amino acid β-alanine and pantoic acid (see #Biosynthesis, biosynthesis and structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Fatty Acid Synthase
Fatty acid synthase (FAS) is an enzyme that in humans is encoded by the ''FASN'' gene. Fatty acid synthase is a multi-enzyme protein that catalyzes fatty acid synthesis. It is not a single enzyme but a whole enzymatic system composed of two identical 272 kDa multifunctional polypeptides, in which Substrate (biochemistry), substrates are handed from one functional domain to the next. Its main function is to catalyze the synthesis of palmitic acid, palmitate (C16:0, a long-chain Saturated fat, saturated fatty acid) from acetyl-CoA and malonyl-CoA, in the presence of nicotinamide adenine dinucleotide phosphate, NADPH. The fatty acids are synthesized by a series of decarboxylative Claisen condensation reactions from acetyl-CoA and malonyl-CoA. Following each round of elongation the beta keto group is reduced to the fully saturated carbon chain by the sequential action of a Beta-Ketoacyl ACP reductase, ketoreductase (KR), dehydratase (DH), and Enoyl-acyl carrier protein reductase, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Polyketide Synthase
Polyketide synthases (PKSs) are a family of multi- domain enzymes or enzyme complexes that produce polyketides, a large class of secondary metabolites, in bacteria, fungi, plants, and a few animal lineages. The biosyntheses of polyketides share striking similarities with fatty acid biosynthesis. The PKS genes for a certain polyketide are usually organized in one operon or in gene clusters. Type I and type II PKSs form either large modular protein complexes or dissociable molecular assemblies; type III PKSs exist as smaller homodimeric proteins. Classification PKSs can be classified into three types: * Type I PKSs are large, complex protein structures with multiple modules which in turn consist of several domains that are usually covalently connected to each other and fulfill different catalytic steps. The minimal composition of a type I PKS module consists of an acyltransferase (AT) domain, which is responsible for choosing the building block to be used, a keto synthase (KS) do ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Acyl Carrier Protein
The acyl carrier protein (ACP) is a cofactor of both fatty acid and polyketide biosynthesis machinery. It is one of the most abundant proteins in cells of ''E. coli.'' In both cases, the growing chain is bound to the ACP via a thioester derived from the distal thiol of a 4'-phosphopantetheine moiety. Structure The ACPs are small negatively charged α-helical bundle proteins with a high degree of structural and amino acid similarity. The structures of a number of acyl carrier proteins have been solved using various NMR and crystallography techniques. The ACPs are related in structure and mechanism to the peptidyl carrier proteins (PCP) from nonribosomal peptide synthases. Biosynthesis Subsequent to the expression of the inactive ''apo'' ACP, the 4'-phosphopantetheine moiety is attached to a serine residue. This coupling is mediated by acyl carrier protein synthase (ACPS), a 4'-phosphopantetheinyl transferase. 4'-Phosphopantetheine is a prosthetic group of several acyl carrier pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Nonribosomal Peptide Synthetases
Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacteria inside these organisms. While there exist a wide range of peptides that are not synthesized by ribosomes, the term ''nonribosomal peptide'' typically refers to a very specific set of these as discussed in this article. Nonribosomal peptides are synthesized by nonribosomal peptide synthetases, which, unlike the ribosomes, are independent of messenger RNA. Each nonribosomal peptide synthetase can synthesize only one type of peptide. Nonribosomal peptides often have cyclic and/or branched structures, can contain non- proteinogenic amino acids including D-amino acids, carry modifications like '' N''-methyl and ''N''-formyl groups, or are glycosylated, acylated, halogenated, or hydroxylated. Cyclization of amino acids against t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Formyltetrahydrofolate Dehydrogenase
In enzymology, a formyltetrahydrofolate dehydrogenase () is an enzyme that catalyzes the chemical reaction :10-formyltetrahydrofolate + NADP+ + H2O \rightleftharpoons tetrahydrofolate + CO2 + NADPH + H+ The 3 substrates of this enzyme are 10-formyltetrahydrofolate, NADP+, and H2O, whereas its 4 products are tetrahydrofolate, CO2, NADPH, and H+. This enzyme belongs to the family of oxidoreductases, to be specific those acting on the CH-NH group of donors with NAD+ or NADP+ as acceptor. The systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ... of this enzyme class is 10-formyltetrahydrofolate:NADP+ oxidoreductase. Other names in common use include 10-formyl tetrahydrofolate:NADP oxidoreductase, 10-formyl-H2PtGlu:NADP oxidoreductase, 10-formyl-H4folate dehydrogen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Serine
Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α- amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form under biological conditions), and a side chain consisting of a hydroxymethyl group, classifying it as a polar amino acid. It can be synthesized in the human body under normal physiological circumstances, making it a nonessential amino acid. It is encoded by the codons UCU, UCC, UCA, UCG, AGU and AGC. Occurrence This compound is one of the proteinogenic amino acids. Only the L- stereoisomer appears naturally in proteins. It is not essential to the human diet, since it is synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865 by Emil Cramer. Its name is derived from the Latin for silk, '' sericum''. Serine's structure was established in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Phosphodiester
In chemistry, a phosphodiester bond occurs when exactly two of the hydroxyl groups () in phosphoric acid react with hydroxyl groups on other molecules to form two ester bonds. The "bond" involves this linkage . Discussion of phosphodiesters is dominated by their prevalence in DNA and RNA, but phosphodiesters occur in other biomolecules, e.g. acyl carrier proteins, phospholipids and the cyclic forms of GMP and AMP (cGMP and cAMP). Phosphodiester Backbone of DNA and RNA Phosphodiester bonds make up the backbones of DNA and RNA. In the phosphodiester bonds of nucleic acids, a phosphate is attached to the 5' carbon of one nucleoside and to the 3' carbon of the adjacent nucleoside. Specifically, it is the phosphodiester bonds that link the 3' carbon atom of one sugar molecule and the 5' carbon atom of another (hence the name 3', 5' phosphodiester linkage used with reference to this kind of bond in DNA and RNA chains). The involved saccharide groups are deoxyribose in DNA and rib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Thioester Bond
In organic chemistry, thioesters are organosulfur compounds with the molecular structure . They are analogous to carboxylate esters () with the sulfur in the thioester replacing oxygen in the carboxylate ester, as implied by the thio- prefix. They are the product of esterification of a carboxylic acid () with a thiol (). In biochemistry, the best-known thioesters are derivatives of coenzyme A, e.g., acetyl-CoA.Matthys J. Janssen "Carboxylic Acids and Esters" in PATAI's Chemistry of Functional Groups: Carboxylic Acids and Esters, Saul Patai, Ed. John Wiley, 1969, New York: pp. 705–764. The R and R' represent organyl groups, or H in the case of R. Synthesis One route to thioesters involves the reaction of an acid chloride with an alkali metal salt of a thiol: : Another common route entails the displacement of halides by the alkali metal salt of a thiocarboxylic acid. For example, thioacetate esters are commonly prepared by alkylation of potassium thioacetate: : The analogous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
