- Valinomycin
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ImageFile = Valinomycin.svg
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Formula = C54H90N6O18
Section1 = Chembox Identifiers
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CASNo = 2001-95-8
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Section2 = Chembox Properties
MolarMass = 1111.32
Appearance = White solid
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MeltingPt = 172°C -177 °C
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SolubleOther = Methanol, Ethanol, Ethyl acetate, Petrol-ether, Dichloromethane
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Section3 = Chembox Structure
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Section5 = Chembox Pharmacology
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Section6 = Chembox Explosive
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Section7 = Chembox Hazards
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MainHazards = Neurotoxicant
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Section8 = Chembox Related
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OtherCpds =Valinomycin is a dodecadepsipeptide, that is, it is made of twelve alternating
amino acid s andester s to form a macrocyclic molecule.Valinomycin is obtained from the cells of several
Streptomyces strains, one of them Str. Tsusimaensis.It is a member of the group of natural neutral
ionophore s because it doesn't have a residual charge. It consists ofenantiomer es D- and L-Valine, D-Hydroxyvaleric acid and L-Lactic acid . Structures are alternated bound viaamide andester bridges. Valinomycin is highly selective forpotassium ions oversodium ions within thecell membrane . [cite journal | author=Rose Lars and Jenkins ATA | title=The effect of the ionophore valinomycin on biomimetic solid supported lipid DPPTE/EPC membranes | journal=Bioelectrochem. | year=2007 | volume=70 | issue=2 | pages=387–393 | doi=10.1016/j.bioelechem.2006.05.009 Entrez Pubmed|16875886] It functions as a potassium-specific transporter and facilitates the movement of potassium ions through lipid membranes "down" an electrochemical potential gradient. [cite journal | author=Cammann K | title=Ion-selective bulk membranes as models | journal=Top. Curr. Chem. | year=1985 | volume=128 | pages=219–258] Thestability constant K for the potassium-valinomycin complex is 106 and for the sodium-valinomycin complex only 10. This difference is important for maintaining the selectivity of valinomycin for the transport of potassium ions (and not sodium ions) in biological systems.tructure
Note these salient features and implications of the chemical structure: The 12
carbonyl groups are essential for the binding of metal ions, and also forsolvation in polar solvent. Theisopropyl groups andmethyl groups are responsible for solvation in nonpolar solvents. [cite journal | author=Thompson M and Krull UJ | title=The electroanalytical response of the bilayer lipid membrane to valinomycin: membrane cholesterol content | journal=Anal. Chim. Acta | year=1982 | volume=141 | pages=33–47 | doi=10.1016/S0003-2670(01)95308-5] Along with its shape and size this molecular duality is the main reason for its binding properties. For polar solvents valinomycin will mainly expose the carbonyls to the solvent and in nonpolar solvents the iso-propyl groups are located predominantly on the exterior of the molecule. This conformation changes when valinomycin is bound to a potassium ion. The molecule is "locked" into a conformation with the isopropyl groups on the exterior. It is not actually locked into configuration because the size of the molecule makes it highly flexible, but the potassium ion gives some degree of coordination to the macromolecule.Application
Valinomycin acts as ion-exchange agent in
Potassium selective electrode . [cite journal | author= Safiulina D, Veksler V, Zharkovsky A and Kaasik A | title=Loss of mitochondrial membrane potential is associated with increase in mitochondrial volume: physiological role in neurones | journal= J Cell Physiol | year=2006 | volume=206 | issue=2 | pages=347–353 | doi=10.1002/jcp.20476 Entrez Pubmed|16110491]References
External links
* [http://www.state.nj.us/health/eoh/rtkweb/2850.pdf Chemical Safety Regulations] from
New Jersey Department of Health .
* [http://www.scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=2001-95-8 Health information on Scorecard] .
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