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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 concentrati ... [...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 concentrati ... [...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 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 its deriva ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nigericin
Nigericin is an antibiotic derived from '' Streptomyces hygroscopicus''. Its isolation was described in the 1950s, 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, 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 oligomers of the innate immune system responsible for the activation of inflammatory responses. Activation and assembly of the inflammasome promotes proteolytic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of cells and organelles, being selectively permeable to ions a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plants
Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclude the fungi and some algae, as well as the prokaryotes (the archaea and bacteria). By one definition, plants form the clade Viridiplantae (Latin name for "green plants") which is sister of the Glaucophyte, Glaucophyta, and consists of the green algae and Embryophyte, Embryophyta (land plants). The latter includes the flowering plants, conifers and other gymnosperms, ferns and Fern ally, their allies, hornworts, liverworts, and mosses. Most plants are multicellular organisms. Green plants obtain most of their energy from sunlight via photosynthesis by primary chloroplasts that are derived from endosymbiosis with cyanobacteria. Their chloroplasts contain chlorophylls a and b, which gives them their green colo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siderophores
Siderophores (Greek: "iron carrier") are small, high-affinity iron-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+ complexes that can be taken up by active transport mechanisms. Many siderophores are nonribosomal peptides, although several are biosynthes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Species
A chemical species is a chemical substance or ensemble composed of chemically identical molecular entity, molecular entities that can explore the same set of molecular energy levels on a characteristic or delineated time scale. These energy levels determine the way the chemical species will interact with others (engaging in chemical bonds, etc.). The species can be an atom, molecule, ion, or radical, and it has a specific chemical name and chemical formula. The term is also applied to a set of chemically identical atomic or molecular structural units in a solid array. In supramolecular chemistry, chemical species are those supramolecular structures whose interactions and associations are brought about via intermolecular bonding and debonding actions, and function to form the basis of this branch of chemistry. For instance: * The chemical species argon is an atom, atomic species of formula Ar; * dioxygen and ozone are different molecule, molecular species, of respective formulas O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.However, most of the universe's mass is not in the form of baryons or chemical elements. See dark matter and dark energy. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nystatin
Nystatin, sold under the brandname Mycostatin among others, is an antifungal medication. It is used to treat '' Candida'' infections of the skin including diaper rash, 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 World Health Organization's List of Essential Medicines. It is available as a generic medication. It is made from the bacterium '' Streptomyces noursei'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gramicidin
Gramicidin, also called gramicidin D, is a mix of ionophoric antibiotics, gramicidin A, B and C, which make up about 80%, 5%, and 15% of the mix, respectively. Each has 2 isoforms, so the mix has 6 different types of gramicidin molecules. They can be extracted from ''Brevibacillus brevis'' soil bacteria. Gramicidins are linear peptides with 15 amino acids. This is in contrast to unrelated gramicidin S, which is a cyclic peptide. Medical uses Gramicidins work as antibiotics against gram-positive bacteria like ''Bacillus subtilis'' and ''Staphylococcus aureus'', but not well against gram-negative ones like '' E. coli''. Gramicidins are used in medicinal lozenges for sore throat and in topical medicines to treat infected wounds. Gramicidins are often mixed with other antibiotics like tyrocidine and antiseptics. Gramicidins are also used in eye drops for bacterial eye infections. In drops, they are often mixed with other antibiotics like polymyxin B or neomycin. Multiple antibioti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
