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Siderophores
Siderophores (Greek: "iron carrier") are small, high-affinity iron-Chelation, chelating compounds that are secreted by microorganisms such as bacteria and fungi. They help the organism accumulate iron. Although a widening range of siderophore functions is now being appreciated, siderophores are among the strongest (highest affinity) Fe3+ binding agents known. Phytosiderophores are siderophores produced by plants. Scarcity of soluble iron Despite being one of the most abundant elements in the Earth's crust, iron is not readily bioavailable. In most aerobic environments, such as the soil or sea, iron exists in the ferric (Fe3+) state, which tends to form insoluble rust-like solids. To be effective, nutrients must not only be available, they must be soluble. Microbes release siderophores to scavenge iron from these mineral phases by formation of soluble Fe3+ Complex (chemistry), complexes that can be taken up by active transport mechanisms. Many siderophores are nonribosomal peptides, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siderocalin
Siderocalin (Scn), lipocalin-2, NGAL, 24p3 is a mammalian lipocalin-type protein that can prevent iron acquisition by pathogenic bacteria by binding siderophores, which are iron-binding chelators made by microorganisms. Iron serves as a key nutrient in host (biology), host-pathogen interactions, and pathogens can acquire iron from the host organism via Biosynthesis, synthesis and release siderophores such as enterobactin. Siderocalin is a part of the mammalian defence mechanism and acts as an antibacterial agent. Crystallographic studies of Scn demonstrated that it includes a wikt:calyx, calyx, a ligand-binding domain that is lined with polar cationic groups. Central to the siderophore/siderocalin recognition mechanism are hybrid electrostatic/cation-pi interactions. To evade the host defences, pathogens evolved to produce structurally varied siderophores that would not be recognized by siderocalin, allowing the bacteria to acquire iron. Iron requirements of host organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enterobactin
Enterobactin (also known as enterochelin) is a high affinity siderophore that acquires iron for microbial systems. It is primarily found in Gram-negative bacteria, such as ''Escherichia coli'' and ''Salmonella typhimurium''. Enterobactin is the strongest siderophore known, binding to the ferric ion (Fe3+) with affinity K = 1052 M−1. This value is substantially larger than even some synthetic metal chelators, such as EDTA (Kf,Fe3+ ~ 1025 M−1). Due to its high affinity, enterobactin is capable of chelating even in environments where the concentration of ferric ion is held very low, such as within living organisms. Pathogenic bacteria can steal iron from other living organisms using this mechanism, even though the concentration of iron is kept extremely low due to the toxicity of free iron. Structure and biosynthesis Chorismic acid, an aromatic amino acid precursor, is converted to 2,3-dihydroxybenzoic acid (DHB) by a series of enzymes, EntA, EntB and EntC. An amide linkage of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deferoxamine
Deferoxamine (DFOA), also known as desferrioxamine and sold under the brand name Desferal, is a medication that binds iron and aluminium. It is specifically used in iron overdose, hemochromatosis either due to multiple blood transfusions or an underlying genetic condition, and aluminium toxicity in people on dialysis. It is used by injection into a muscle, vein, or under the skin. Common side effects include pain at the site of injection, diarrhea, vomiting, fever, hearing loss, and eye problems. Severe allergic reactions including anaphylaxis and low blood pressure may occur. It is unclear if use during pregnancy or breastfeeding is safe for the baby. Deferoxamine is a siderophore from the bacteria '' Streptomyces pilosus''. Deferoxamine was approved for medical use in the United States in 1968. It is on the World Health Organization's List of Essential Medicines. Medical uses Deferoxamine is used to treat acute iron poisoning, especially in small children. This agent i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust, being mainly deposited by meteorites in its metallic state. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching , about 500 °C (900 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to displace copper alloys – in some regions, only around 1200 BC. That event is considered the transition from the Bronze Age to the Iron Age. In the modern world, iron alloys, such as steel, stainless steel, cast iron and special steels, are by far the most common industrial metals, due to their mechan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petrobactin
Petrobactin is a bis-catechol siderophore found in Marinobacter hydrocarbonoclasticus, M. hydrocarbonoclasticus, Alteromonas macleodii, A. macleodii, and the anthrax-producing Bacillus anthracis, B. anthracis. Like other siderophores petrobactin is a highly specific iron(III) transport ligand, contributing to the Siderophore#Marine water, marine microbial uptake of environmental iron. The iron-Chelation, chelated petrobactin complex readily undergoes a Photodissociation, photolytic oxidative decarboxylation due to its α-hydroxy carboxylate group, converting iron(III) to the more biologically useful iron(II). Biological function Like other siderophores, petrobactin is secreted by an animal pathogenic bacterium. B. anthracis uses petrobactin to acquire iron from its host. Interestingly, while the 3,4-catecholate ends of petrobactin do not improve iron(III) affinity relative to hydroxamate ends, they speed up iron removal from human diferric transferrin. Petrobactin in its fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillibactin
Bacillibactin is a catechol-based siderophore secreted by members of the genus ''Bacillus'', including ''Bacillus anthracis'' and ''Bacillus subtilis''. It is involved in the chelation of ferric iron (Fe3+) from the surrounding environment and is subsequently transferred into the bacterial cytoplasm via the use of ABC transporters. Biosynthesis The biosynthetic pathway of bacillibactin was first identified by May et al. in the Gram-positive '' B. subtilis''. The siderophore is synthesized through multimodular non ribosomal peptide synthetases (NRPS), similar to enterobactin. However, unlike enterobactin, the genes responsible for encoding the bacillibactin synthetases are all located in one operon. This gene cluster is termed ''dhb'' – cognate to the catecholic structure of 2,3-dihydroxybenzoate (DHB) – and it can be divided into the specific genes responsible for encoding the enzymes. The three genes are ''dhbE, dhbB,'' and ''dhbF'', which get translated into DhbE, DhbB, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexadentate
A hexadentate ligand in coordination chemistry is a ligand that combines with a central metal atom with six bonds. One example of a hexadentate ligand that can form complexes with soft metal ions is TPEN. A commercially important hexadentate ligand is EDTA. The denticity of hexadentate ligands is often denoted with the prefix κ6. Topology The way the donor atoms are joined together in the molecule is its topology. Some topologies are simple, such as the linear or ring shapes. The molecule can also be branched, either at a donor atom, or at a non-donor atom. Example shapes are the tripod, and amplector, with a bifurcation at each end. Rigid molecules can be used to force unusual coordination such as trigonal prism In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The oc .... F. Lions identif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reduction (chemistry)
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: * Electron transfer, Electron-transfer – Only one (usually) electron flows from the atom, ion, or molecule being oxidized to the atom, ion, or molecule that is reduced. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * Atom transfer – An atom transfers from one Substrate (chemistry), 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 r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extracellular
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology, Glossary of environmental science and Glossary of scientific naming, or any of the organism-specific glossaries in :Glossaries of biology. A B C D E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme
Heme (American English), or haem (Commonwealth English, both pronounced /Help:IPA/English, hi:m/ ), is a ring-shaped iron-containing molecule that commonly serves as a Ligand (biochemistry), ligand of various proteins, more notably as a Prosthetic group, component of hemoglobin, which is necessary to bind oxygen in the bloodstream. It is composed of four pyrrole rings with 2 Vinyl group, vinyl and 2 propionic acid side chains. Heme is biosynthesized in both the bone marrow and the liver. Heme plays a critical role in multiple different redox reactions in mammals, due to its ability to carry the oxygen molecule. Reactions include oxidative metabolism (cytochrome c oxidase, succinate dehydrogenase), xenobiotic detoxification via cytochrome P450 pathways (including Drug metabolism, metabolism of some drugs), gas sensing (Guanylate cyclase, guanyl cyclases, nitric oxide synthase), and microRNA processing (DGCR8). Heme is a coordination complex "consisting of an iron ion coordinated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalassemia
Thalassemias are a group of Genetic disorder, inherited blood disorders that manifest as the production of reduced hemoglobin. Symptoms depend on the type of thalassemia and can vary from none to severe, including death. Often there is mild to severe anemia (low red blood cells or hemoglobin) as thalassemia can affect the production of red blood cells and also affect how long the red blood cells live. Symptoms include fatigue (medical), tiredness, pallor, bone problems, an splenomegaly, enlarged spleen, jaundice, pulmonary hypertension, and dark urine. A child's growth and development may be slower than normal. Thalassemias are genetic disorders. Alpha thalassemia is caused by deficient production of the Hemoglobin subunit alpha, alpha globin component of hemoglobin, while beta thalassemia is a deficiency in the Hemoglobin subunit beta, beta globin component. The severity of alpha and beta thalassemia depends on how many of the four genes for alpha globin or two genes for beta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
