Ionophore

Ionophore

An ionophore is a lipid-soluble molecule usually synthesized by microorganisms to transport ions across the lipid bilayer of the cell membrane. There are two broad classifications of ionophores.

# Small molecules (mobile ion carriers) that bind to a particular ion, shielding its charge from the surrounding environment, and thus facilitating its crossing of the hydrophobic interior of the lipid membrane.
# Channel formers that introduce a hydrophilic pore into the membrane, allowing ions to pass through while avoiding contact with the membrane's hydrophobic interior.

Ionophores disrupt transmembrane ion concentration gradients, required for the proper functioning and survival of microorganisms, and thus have antibiotic properties. They are produced naturally by certain microbes and act as a defense against competing microbes.

In laboratory research, ionophores are used to increase the permeability of biological membranes to certain ions. Additionally, some ionophores are used as antibiotics and/or as growth enhancing feed additives for certain food animals such as cattle (see monensin). The U.S. Department of Agriculture sent a letter to Tyson Foods to remove labels for chickens that said "raised without antibiotics" because of the use of ionophores in their feed. [cite website | first = Marcus | last = Kabel | coauthors = Christine Simmons | title = USDA Revokes OK for Tyson Chicken Labels | date = 2007-11-20 | url = http://ap.google.com/article/ALeqM5iYfYJmjwYMb-6RiqjCbJ481k5xjgD8T16P5O0 | accessdate = 2007-11-20]

Representative ionophores (with the ion(s) they act upon):

* 2,4-Dinitrophenol (H+)
* Beauvericin (Ca2+, Ba2+)
* Calixarene
* Calcimycine (A23187)
* Carbonyl cyanide m-chlorophenyl hydrazone
* Crown ether
* FCCP or Carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (H+)
* Gramicidin A (H+, Na+, K+)
* Ionomycin (Ca2+)
* Lasalocid
* Monensin (Na+, H+)
* Nigericin (K+, H+, Pb2+)
* Nonactin (Ammonium ionophore I)
* Nystatin
* Proton ionophore II (4-Nonadecylpyridine)
* Proton ionophore III (N,N-Dioctadecylmethylamine)
* Salinomycin (K+)
* Valinomycin (K+)

References


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Look at other dictionaries:

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  • ionophore — i*on o*phore n. [ion + phore] (Biochemistry) A compound that enhances transport of ions across cellular membranes, by binding them and carrying them across. As a class ionophores tend to be lipophilic in nature; each compound is usually specific… …   The Collaborative International Dictionary of English

  • ionophore — ● ionophore nom masculin Molécule ou groupement de molécules présents dans les membranes des cellules nerveuses et musculaires qui régissent les transferts ioniques au travers des membranes …   Encyclopédie Universelle

  • ionophore — [ī än′ə fôr΄] n. any of a group of compounds that transport, across a plasma membrane, ions which are not able to cross by themselves; esp., any of certain antibiotics, as valinomycin …   English World dictionary

  • Ionophore — Ein Ionophor ist ein Molekül, das Ionen durch eine Membran transportiert. Einige Bakterien bilden Ionophore, also Moleküle, die die Permeabilität von Membranen für Ionen erhöhen. Oft haben solche Moleküle eine antibiotische Wirkung, da sie das… …   Deutsch Wikipedia

  • Ionophore — Un soluté ionophore (phore = qui porte) est un soluté qui porte des ions. C est le cas des composés solides ioniques tels que chlorure de sodium ou CaF2. Opposé à Ionogène. Dans la cellule, on distingue deux types d ionophores qui permettent le… …   Wikipédia en Français

  • ionophore — jonoforas statusas T sritis chemija apibrėžtis Medžiaga, padidinanti biomembranos pralaidumą jonams. atitikmenys: angl. ionophore rus. ионофор …   Chemijos terminų aiškinamasis žodynas

  • ionophore — noun Date: circa 1955 a compound that facilitates transmission of an ion (as of calcium) across a lipid barrier (as in a cell membrane) by combining with the ion or by increasing the permeability of the barrier to it …   New Collegiate Dictionary

  • ionophore — A molecule that allows ions to cross lipid bilayers. There are two classes: carriers and channels. Carriers, like valinomycin, form cage like structures around specific ions, diffusing freely through the hydrophobic regions of the bilayer.… …   Dictionary of molecular biology

  • ionophore — /uy on euh fawr , fohr /, n. Biochem. a lipid soluble substance capable of transporting specific ions through cellular membranes. [1950 55; IONO + PHORE] * * * …   Universalium

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