What is the role of valinomycin?
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.
Why are molecules such as valinomycin effective at transporting ions across the membrane?
Because valinomycin is uncharged and contains no ionisable groups, it acquires the charge of the complexed ion. Both the uncomplexed and the complexed forms of valinomycin are able to diffuse across the membrane. Therefore, a catalytic amount of ionophore can induce the bulk transport of cations.
Why is valinomycin toxic?
Valinomycin and cereulide are bacterial toxins with closely similar chemical structure and properties but different toxic effects. Emetic poisoning is induced by cereulide but not by valinomycin. Both are specific potassium ionophores. Such compounds may affect mitochondrial functions.
How does valinomycin work as an antibiotic?
How does valinomycin affect cellular respiration?
Valinomycin produces higher steady state potassium phosphate swelling which can be reversed to give active shrinkage if mersalyl is added to block the Pi−/OH− antiporter. Respiration declines concurrently. Uncouplers accelerate the shrinkage and restore the respiration.
Is valinomycin an uncoupler?
Valinomycin in the presence of potassium is a potent uncoupler of corn (Zea mays L.) mitochondria, eliminating respiratory control. Valinomycin produces higher steady state potassium phosphate swelling which can be reversed to give active shrinkage if mersalyl is added to block the Pi−/OH− antiporter.
How does Valinomycin affect cellular respiration?
How does Valinomycin affect ATP synthesis?
Magnesium ions were shown to have an inhibitor effect on the K+ uptake, and stimulated a greater rate of ATP synthesis. When valinomycin and ADP were added simultaneously so that phosphorylation of the ADP and enhancement of K+ uptake could complete for mitochondrial energy, K+ uptake was preferred over ATP synthesis.
Why is valinomycin a powerful antibiotic valinomycin is an example of what type of transport?