Valinomycin
Cyclo-(D - α -D -valyl - hydroxyisovaleryl -L- lactoyl -L -valyl -D - α -D -valyl - hydroxyisovaleryl -L- lactoyl -L -valyl -D - α -D -valyl - hydroxyisovaleryl -L- lactoyl -L-valyl )
Beige solid
Fixed
190 ° C ( decomposition)
Insoluble in water
Risk
4 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search available
Valinomycin is a depsipeptide Cyclo Deka and is one of the macrolide antibiotics. It is (for example, Streptomyces fulvissimus ) produced by several species of Streptomyces.
Structure
Valinomycin consists of the enantiomeric amino acids L- valine and D-valine, as well as hydroxy acids L-lactate and D- Hydroxyisovalerat. The cyclic structure, consisting of the triple repeat tetra depsipeptide unit [ -L -Lac -L -Val- D- Hiv -D -Val- ] 3, forms a symmetrical ring 36 atoms of alternating amide and ester bonds.
Properties
Valinomycin is an ionophore that selectively transports potassium ions. Where K is complexed in a cage-like structure and be transported through the cell membrane. Through these transport processes collapses the membrane potential and the cell dies.
The complex formation constant for the potassium - valinomycin complex is 106, whereas it is the sodium - valinomycin complex only at 10. This large difference (selectivity ) for the transport processes in biological systems is of great importance.
Use
Most of the electrodes for the detection of potassium ions, the specific use of the complexation of potassium ions by valinomycin, which is embedded in a concentration of about 0.7% in a plastic membrane.