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Non-heme Iron Protein
In biochemistry, non-heme iron proteins describe families of enzymes that utilize iron at the active site but lack heme cofactors. Iron-sulfur proteins, including those that are enzymes, are not included in this definition. Some of non-heme iron proteins contain one Fe at their active sites, others have pairs of Fe centers: *Many mono-Fe proteins are alpha-ketoglutarate-dependent hydroxylases. Major examples are the lipoxygenases, isopenicillin N synthase, protocatechuate 3,4-dioxygenase, deacetoxycephalosporin-C synthase, and aromatic amino acid hydroxylases. *Major diiron enzymes include hemerythrin, some ribonucleotide reductases, some methane monooxygenases, purple acid phosphatases, and ferritin Ferritin is a universal intracellular protein that stores iron and releases it in a controlled fashion. The protein is produced by almost all living organisms, including archaea, bacteria, algae, higher plants, and animals. It is the primary ' ....{{cite journal , doi=10.1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells,Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function.Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.As ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme
Heme, or haem (pronounced / hi:m/ ), is a precursor to hemoglobin, which is necessary to bind oxygen in the bloodstream. Heme is biosynthesized in both the bone marrow and the liver. In biochemical terms, heme is a coordination complex "consisting of an iron ion coordinated to a porphyrin acting as a tetradentate ligand, and to one or two axial ligands." The definition is loose, and many depictions omit the axial ligands. Among the metalloporphyrins deployed by metalloproteins as prosthetic groups, heme is one of the most widely used and defines a family of proteins known as hemoproteins. Hemes are most commonly recognized as components of hemoglobin, the red pigment in blood, but are also found in a number of other biologically important hemoproteins such as myoglobin, cytochromes, catalases, heme peroxidase, and endothelial nitric oxide synthase. The word ''haem'' is derived from Greek ''haima'' meaning "blood". Function Hemoproteins have diverse biological functions incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron-sulfur Protein
Iron–sulfur proteins (or iron–sulphur proteins in British spelling) are proteins characterized by the presence of iron–sulfur clusters containing sulfide-linked di-, tri-, and tetrairon centers in variable oxidation states. Iron–sulfur clusters are found in a variety of metalloproteins, such as the ferredoxins, as well as NADH dehydrogenase, hydrogenases, coenzyme Q – cytochrome c reductase, succinate – coenzyme Q reductase and nitrogenase. Iron–sulfur clusters are best known for their role in the oxidation-reduction reactions of electron transport in mitochondria and chloroplasts. Both Complex I and Complex II of oxidative phosphorylation have multiple Fe–S clusters. They have many other functions including catalysis as illustrated by aconitase, generation of radicals as illustrated by SAM-dependent enzymes, and as sulfur donors in the biosynthesis of lipoic acid and biotin. Additionally, some Fe–S proteins regulate gene expression. Fe–S proteins are vulnerabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-ketoglutarate-dependent Hydroxylases
Alpha-ketoglutarate-dependent hydroxylases are a major class of non-heme iron proteins that catalyse a wide range of reactions. These reactions include hydroxylation reactions, demethylations, ring expansions, ring closures, and desaturations. Functionally, the αKG-dependent hydroxylases are comparable to cytochrome P450 enzymes. Both use O2 and reducing equivalents as cosubstrates and both generate water. Biological function αKG-dependent hydroxylases have diverse roles. In microorganisms such as bacteria, αKG-dependent dioxygenases are involved in many biosynthetic and metabolic pathways; for example, in ''E. coli'', the AlkB enzyme is associated with the repair of damaged DNA. In plants, αKG-dependent dioxygenases are involved in diverse reactions in plant metabolism. These include flavonoid biosynthesis, and ethylene biosyntheses. In mammals and humans, αKG-dependent dioxygenase have functional roles in biosyntheses (e.g. collagen biosynthesis and L-carnitine biosynthe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipoxygenase
Lipoxygenases () are a family of (non-heme) iron-containing enzymes most of which catalyze the dioxygenation of polyunsaturated fatty acids in lipids containing a cis,cis-1,4- pentadiene into cell signaling agents that serve diverse roles as autocrine signals that regulate the function of their parent cells, paracrine signals that regulate the function of nearby cells, and endocrine signals that regulate the function of distant cells. The lipoxygenases are related to each other based upon their similar genetic structure and dioxygenation activity. However, one lipoxygenase, ALOXE3, while having a lipoxygenase genetic structure, possesses relatively little dioxygenation activity; rather its primary activity appears to be as an isomerase that catalyzes the conversion of hydroperoxy unsaturated fatty acids to their 1,5-epoxide, hydroxyl derivatives. Lipoxygenases are found in eukaryotes (plants, fungi, animals, protists); while the third domain of terrestrial life, the archaea, pos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isopenicillin N Synthase
Isopenicillin N synthase (IPNS) is a non-heme iron protein belongig to the 2-oxoglutarate (2OG)-dependent dioxygenases oxidoreductase family. This enzyme catalyzes the formation of isopenicillin N from δ-(L-α-aminoadipoyl)-L-cysteinyl-D-valine (LLD-ACV). :''N''-[(5''S'')-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine + O2 \rightleftharpoons isopenicillin N + 2 H2O This reaction is a key step in the biosynthesis of penicillin and cephalosporin antibiotics. The active sites of most isopenicillin N synthases contain an iron ion. This enzyme is also called isopenicillin N synthetase. Mechanism A Fe(II) metal ion in the active site of the enzyme is coordinated by at least two histidine residues, an aspartate residue, a glutamine residue, and two water molecules in the absence of a bound Substrate (biochemistry), substrate. Just two histidine residues and one aspartic acid residue are entirely conserved. Therefore, it is highly significant that these two histidine residues, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protocatechuate 3,4-dioxygenase
In enzymology, a protocatechuate 3,4-dioxygenase () is an enzyme that catalyzes the chemical reaction : 3,4-dihydroxybenzoate + O2 \rightleftharpoons 3-carboxy-cis,cis-muconate Thus, the two substrates of this enzyme are 3,4-dihydroxybenzoate (protocatechuic acid) and O2, whereas its product is 3-carboxy-cis,cis-muconate. This enzyme belongs to the family of oxidoreductases, specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate (oxygenases). The systematic name of this enzyme class is protocatechuate:oxygen 3,4-oxidoreductase (decyclizing). Other names in common use include protocatechuate oxygenase, protocatechuic acid oxidase, protocatechuic 3,4-dioxygenase, and protocatechuic 3,4-oxygenase. This enzyme participates in benzoate degradation via hydroxylation and 2,4-dichlorobenzoate degradation. It employs one cofactor, iron. This enzyme has been found effective at improving organic fluorophore-stabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deacetoxycephalosporin-C Synthase
In enzymology, a deacetoxycephalosporin-C synthase () is an enzyme that catalyzes the chemical reaction penicillin N + 2-oxoglutarate + O2 \rightleftharpoons deacetoxycephalosporin C + succinate + CO2 + H2O The 3 substrates of this enzyme are penicillin N, 2-oxoglutarate, and O2, whereas its 4 products are deacetoxycephalosporin C, succinate, CO2, and H2O. Classification This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with 2-oxoglutarate as one donor, and the other dehydrogenated. Nomenclature The systematic name of this enzyme class is penicillin-N,2-oxoglutarate:oxygen oxidoreductase (ring-expanding). Other names in common use include DAOCS, penicillin N expandase, and DAOC synthase. Biological role This enzyme participates in penicillin and cephalosporin biosynthesis. Structural studies As of la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aromatic Amino Acid Hydroxylase
Biopterin-dependent aromatic amino acid hydroxylases (AAAH) are a family of aromatic amino acid hydroxylase enzymes which includes phenylalanine 4-hydroxylase (), tyrosine 3-hydroxylase (), and tryptophan 5-hydroxylase (). These enzymes primarily hydroxylate the amino acids L-phenylalanine, L-tyrosine, and L-tryptophan, respectively. The AAAH enzymes are functionally and structurally related proteins which act as rate-limiting catalysts for important metabolic pathways. Each AAAH enzyme contains iron and catalyzes the ring hydroxylation of aromatic amino acids using tetrahydrobiopterin (BH4) as a substrate. The AAAH enzymes are regulated by phosphorylation at serines in their N-termini. Role in metabolism In humans, phenylalanine hydroxylase deficiency can cause phenylketonuria, the most common inborn error of amino acid metabolism. Phenylalanine hydroxylase catalyzes the conversion of to . Tyrosine hydroxylase catalyzes the rate-limiting step in catecholamine biosynthesis: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deacetoxycephalosporin-C Synthase
In enzymology, a deacetoxycephalosporin-C synthase () is an enzyme that catalyzes the chemical reaction penicillin N + 2-oxoglutarate + O2 \rightleftharpoons deacetoxycephalosporin C + succinate + CO2 + H2O The 3 substrates of this enzyme are penicillin N, 2-oxoglutarate, and O2, whereas its 4 products are deacetoxycephalosporin C, succinate, CO2, and H2O. Classification This enzyme belongs to the family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with 2-oxoglutarate as one donor, and the other dehydrogenated. Nomenclature The systematic name of this enzyme class is penicillin-N,2-oxoglutarate:oxygen oxidoreductase (ring-expanding). Other names in common use include DAOCS, penicillin N expandase, and DAOC synthase. Biological role This enzyme participates in penicillin and cephalosporin biosynthesis. Structural studies As of la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemerythrin
Hemerythrin (also spelled haemerythrin; grc, αἷμα, haîma, blood, grc, ἐρυθρός, erythrós, red) is an oligomeric protein responsible for oxygen (O2) transport in the marine invertebrate phyla of sipunculids, priapulids, brachiopods, and in a single annelid worm genus, ''Magelona''. Myohemerythrin is a monomeric O2-binding protein found in the muscles of marine invertebrates. Hemerythrin and myohemerythrin are essentially colorless when deoxygenated, but turn a violet-pink in the oxygenated state. Hemerythrin does not, as the name might suggest, contain a heme. The names of the blood oxygen transporters hemoglobin, hemocyanin, hemerythrin, do not refer to the heme group (only found in globins), instead these names are derived from the Greek word for blood. Hemerythrin may also contribute to innate immunity and anterior tissue regeneration in certain worms. O2 binding mechanism The mechanism of dioxygen binding is unusual. Most O2 carriers operate via formation of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribonucleotide Reductase
Ribonucleotide reductase (RNR), also known as ribonucleoside diphosphate reductase (rNDP), is an enzyme that catalyzes the formation of deoxyribonucleotides from ribonucleotides. It catalyzes this formation by removing the 2'-hydroxyl group of the ribose ring of nucleoside diphosphates. This reduction produces deoxyribonucleotides. Deoxyribonucleotides in turn are used in the synthesis of DNA. The reaction catalyzed by RNR is strictly conserved in all living organisms. Furthermore, RNR plays a critical role in regulating the total rate of DNA synthesis so that DNA to cell mass is maintained at a constant ratio during cell division and DNA repair. A somewhat unusual feature of the RNR enzyme is that it catalyzes a reaction that proceeds via a free radical mechanism of action. The substrates for RNR are ADP, GDP, CDP and UDP. dTDP (deoxythymidine diphosphate) is synthesized by another enzyme ( thymidylate kinase) from dTMP (deoxythymidine monophosphate). Structure Ribonucleoti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
