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Ionophore
In chemistry, an ionophore () is a chemical species that reversibly binds ions. Many ionophores are lipid-soluble entities that transport ions across the cell membrane. Ionophores catalyze ion transport across hydrophobic membranes, such as liquid polymeric membranes (carrier-based ion selective electrodes) or lipid bilayers found in the living cells or synthetic vesicles ( liposomes). Structurally, an ionophore contains a hydrophilic center and a hydrophobic portion that interacts with the membrane. Some ionophores are synthesized by microorganisms to import ions into their cells. Synthetic ion carriers have also been prepared. Ionophores selective for cations and anions have found many applications in analysis. These compounds have also shown to have various biological effects and a synergistic effect when combined with the ion they bind. Classification Biological activities of metal ion-binding compounds can be changed in response to the increment of the metal concentr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ionophores
In chemistry, an ionophore () is a chemical species that reversibly binds ions. Many ionophores are lipid-soluble entities that transport ions across the cell membrane. Ionophores catalyze ion transport across hydrophobic membranes, such as liquid polymeric membranes (carrier-based ion selective electrodes) or lipid bilayers found in the living cells or synthetic vesicles (liposomes). Structurally, an ionophore contains a hydrophilic center and a hydrophobic portion that interacts with the membrane. Some ionophores are synthesized by microorganisms to import ions into their cells. Synthetic ion carriers have also been prepared. Ionophores selective for cations and anions have found many applications in analysis. These compounds have also shown to have various biological effects and a synergistic effect when combined with the ion they bind. Classification Biological activities of metal ion-binding compounds can be changed in response to the increment of the metal concentrat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monensin2
Monensin is a polyether antibiotic isolated from ''Streptomyces cinnamonensis''. It is widely used in ruminant animal feeds. The structure of monensin was first described by Agtarap et al. in 1967, and was the first polyether antibiotic to have its structure elucidated in this way. The first total synthesis of monensin was reported in 1979 by Yoshito Kishi, Kishi et al. Mechanism of action Monensin A is an ionophore related to the crown ethers with a preference to form complexes with monovalent cations such as: Li+, Na+, K+, Rb+, Ag+, and Tl+. Monensin A is able to transport these cations across lipid membranes of cells in an electroneutral (i.e. non-depolarizing) exchange, playing an important role as an Na+/H+ antiporter. Recent studies have shown that monensin may transport sodium ion through the membrane in both electrogenic and electroneutral manner. This approach explains ionophoric ability and in consequence antibacterial properties of not only parental monensin, but also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Protonophore
A protonophore, also known as a proton translocator, is an ionophore that moves protons across lipid bilayers or other type of membranes. This would otherwise not occur as protons cations (H+) have positive charge and hydrophilic properties, making them unable to cross without a channel or transporter in the form of a protonophore. Protonophores are generally aromatic compounds with a negative charge, that are both hydrophobic and capable of distributing the negative charge over a number of atoms by π- orbitals which delocalize a proton's charge when it attaches to the molecule. Both the neutral and the charged protonophore can diffuse across the lipid bilayer by passive diffusion and simultaneously facilitate proton transport. Protonophores uncouple oxidative phosphorylation via a decrease in the membrane potential of the inner membrane of mitochondria. They stimulate mitochondria respiration and heat production. Protonophores (uncouplers) are often used in biochemistry research t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valinomycin
Valinomycin is a naturally occurring dodecadepsipeptide used in the transport of potassium and as an antibiotic. Valinomycin is obtained from the cells of several ''Streptomyces'' species, '' S. fulvissimus'' being a notable one. It is a member of the group of natural neutral ionophores because it does not have a residual charge. It consists of enantiomers D- and L-valine (Val), D- alpha-hydroxyisovaleric acid, and L-lactic acid. Structures are alternately bound via amide and ester bridges. Valinomycin is highly selective for potassium ions over sodium ions within the cell membrane. It functions as a potassium-specific transporter and facilitates the movement of potassium ions through lipid membranes "down" the electrochemical potential gradient. The stability constant K for the potassium-valinomycin complex is nearly 100,000 times larger than that of the sodium-valinomycin complex. This difference is important for maintaining the selectivity of valinomycin for the transport of p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nigericin
Nigericin is an antibiotic derived from '' Streptomyces hygroscopicus''. Its isolation from soil from Nigeria was described in the 1950s, by R.L Harned (et. al), and in 1968 the structure could be elucidated by X-ray crystallography. The structure and properties of nigericin are similar to the antibiotic monensin. Commercially it is obtained as a byproduct, or contaminant, at the fermentation of geldanamycin. It is also called polyetherin A, azalomycin M, helixin C, antibiotic K178, and antibiotic X-464. Nigericin acts as an H+, K+, Pb2+ ionophore. Most commonly it is an antiporter of H+ and K+. In the past nigericin was used as an antibiotic active against gram positive bacteria. It inhibits the Golgi functions in Eukaryotic cells. Its ability to induce K+ efflux also makes it a potent activator of the NLRP3 inflammasome Inflammasomes are cytosolic multiprotein complexes of the innate immune system responsible for the activation of inflammatory responses and cell death. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Ether
In organic chemistry, crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups (). The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., . Important members of this series are the tetramer (''n'' = 4), the pentamer (''n'' = 5), and the hexamer (''n'' = 6). The term "crown" refers to the resemblance between the structure of a crown ether bound to a cation, and a crown sitting on a person's head. The first number in a crown ether's name refers to the number of atoms in the cycle, and the second number refers to the number of those atoms that are oxygen. Crown ethers are much broader than the oligomers of ethylene oxide; an important group are derived from catechol. Crown ethers strongly bind certain cations, forming complexes. The oxygen atoms are well situated to coordinate with a cation located at the interior of the ring, whereas the exterior of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Charge
Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwell's equations. Common phenomena are related to electricity, including lightning, static electricity, electric heating, electric discharges and many others. The presence of either a positive or negative electric charge produces an electric field. The motion of electric charges is an electric current and produces a magnetic field. In most applications, Coulomb's law determines the force acting on an electric charge. Electric potential is the Work (physics), work done to move an electric charge from one point to another within an electric field, typically measured in volts. Electricity plays a central role in many modern technologies, serving in electric power where electric current is used to energise equipment, and in electronics dealing w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Species
Chemical species are a specific form of chemical substance or chemically identical molecular entities that have the same molecular energy level at a specified timescale. These entities are classified through bonding types and relative abundance of isotopes. Types of chemical species can be classified based on the type of molecular entity and can be either an atomic, molecular, ionic or radical species. Classification Generally, a chemical species is defined as a chemical identity that has the same set of molecular energy levels in a defined timescale (i.e. an experiment). These energy levels determine the way the chemical species will interact with others through properties such as bonding or isotopic compositions. The chemical species can be an atom, molecule, ion, or radical, with a specific chemical name and chemical formula. In supramolecular chemistry, chemical species are structures created by forming or breaking bonds between molecules, such as hydrogen bonding, dipole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipophilicity
Lipophilicity (from Greek λίπος "fat" and φίλος "friendly") is the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such compounds are called lipophilic (translated as "fat-loving" or "fat-liking"). Such non-polar solvents are themselves lipophilic, and the adage "like dissolves like" generally holds true. Thus lipophilic substances tend to dissolve in other lipophilic substances, whereas hydrophilic ("water-loving") substances tend to dissolve in water and other hydrophilic substances. Lipophilicity, hydrophobicity, and non-polarity may describe the same tendency towards participation in the London dispersion force, as the terms are often used interchangeably. However, the terms "lipophilic" and "hydrophobic" are not synonymous, as can be seen with silicones and fluorocarbons, which are hydrophobic but not lipophilic. __TOC__ Surfactants Hydrocarbon-based surfactants are compounds that are amph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter. Under standard conditions, hydrogen is a gas of diatomic molecules with the chemical formula, formula , called dihydrogen, or sometimes hydrogen gas, molecular hydrogen, or simply hydrogen. Dihydrogen is colorless, odorless, non-toxic, and highly combustible. Stars, including the Sun, mainly consist of hydrogen in a plasma state, while on Earth, hydrogen is found as the gas (dihydrogen) and in molecular forms, such as in water and organic compounds. The most common isotope of hydrogen (H) consists of one proton, one electron, and no neutrons. Hydrogen gas was first produced artificially in the 17th century by the reaction of acids with metals. Henry Cavendish, in 1766–1781, identified hydrogen gas as a distinct substance and discovere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nystatin
Nystatin, sold under the brand name Mycostatin among others, is an antifungal medication. It is used to treat ''Candida (fungus), Candida'' infections of the skin including diaper rash, Candidiasis, thrush, esophageal candidiasis, and vaginal yeast infections. It may also be used to prevent candidiasis in those who are at high risk. Nystatin may be used by mouth, in the vagina, or applied to the skin. Common side effects when applied to the skin include burning, itching, and a rash. Common side effects when taken by mouth include vomiting and diarrhea. During pregnancy use in the vagina is safe while other formulations have not been studied in this group. It works by disrupting the cell membrane of the fungal cells. Nystatin was discovered in 1950 by Rachel Fuller Brown and Elizabeth Lee Hazen. It was the first polyene macrolide antifungal. It is on the WHO Model List of Essential Medicines, World Health Organization's List of Essential Medicines. It is available as a generi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
