How does valinomycin affect mitochondrial electron transfer?
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. Respiration declines concurrently. Uncouplers accelerate the shrinkage and restore the respiration.
What is the function of valinomycin?
Valinomycin is a potent antibiotic. It is commonly used as an agent to induce apoptosis and can also be used to calibrate potentiometric responses in membrane experiments involving potential-sensitive dyes such as di-4-ANEPPS. For Research Use Only. Not for human or animal therapeutic or diagnostic use.
How do valinomycin and gramicidin antibiotics interact with lipid bilayer?
Valinomycin, which is isolated fromStreptomyces fulvissimus, is an example of a carrier molecule that binds K+ and literally ferries it across the lipid bilayer. On the other hand,gramicidin catalyzes K+ movement by the same basic mechanism that has been established for ion channel proteins in cell membranes.
How does Valinomycin inhibit ATP synthesis?
The synthesis is specific for K+- valinomycin as replacement of K+ by Na+ causes a slight and relatively concentration-insensitive ATP synthesis. It is important that the ATP synthesis by valinomycin-treated chloroplasts is reduced to that provided by Na+-valinomycin by the addition of DNP to the K+-valinomycin.
What is the action of gramicidin?
Mechanism of action of gramicidin A. (A) Gramicidin monomers form a β-helix conformation within membranes. Dynamic dimerization of two monomers forms the functional channel, which consequently induces local membrane deformation.
How does valinomycin affect ATP synthesis?
How does Valinomycin affect ATP synthesis?
Is valinomycin an ionophore?
A potassium ionophore (valinomycin) inhibits lymphocyte proliferation by its effects on the cell membrane. See “A potassium ionophore (valinomycin) inhibits lymphocyte proliferation by its effects on the cell membrane” in volume 74 on page 392a. This article has been cited by other articles in PMC.
Why is valinomycin an effective antibiotic agent?
Valinomycin is a potent antibiotic which acts as a potassium (K+) ionophore. Induces K+ conductivity in cell membranes. Also active in vitro against Mycobacterium Tuberculosis, and as an apoptosis inducer.
Does Valinomycin act as an uncoupler or an inhibitor of oxidative phosphorylation?
Valinomycin acts as an uncoupler. It combines K+ to form a complex that passes through the inner mitochondrial membrane, dissipating the membrane potential. ATP synthesis decreases, which causes the rate of electron transfer to increase.
Why is Valinomycin a powerful antibiotic?
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 is Valinomycin an effective antibiotic agent?
How does gramicidin A work as an antibiotic?
Gramicidin A kills bacteria by punching itself through the cell membrane, allowing the cell to leak out and the surroundings to leak in through ion channels. However, these unregulated ion channels can have the same effect on human cells when gramicidin A is used inside the body.
What does Oligomycin do to mitochondria?
Oligomycin prevents the increase in mitochondrial respiration induced by ADP without inhibiting uncoupler-stimulated respiration. NADH remains high and NAD+ is too low for the citric acid cycle to operate.
What things happen when the antibiotic valinomycin is added to actively respiring mitochondria?
When the antibiotic valinomycin is added to actively respiring mitochondria, several things happen: the yield of ATP decreases, the rate of O2 consumption increases, heat is released, and the pH gradient across the inner mitochondrial membrane increases.
What is the function of gramicidin?
Gramicidin inhibits RNA synthesis by purified RNA polymerase (nucleosidetriphosphate:RNA nucleotidyl-transferase, EC 2.7. 7.6) by interfering with the binding of RNA polymerase to DNA.
What is the mechanism of action for gramicidin?
How does oligomycin inhibit ATP synthesis?
Oligomycin is an antibiotic that inhibits ATP synthase by blocking its proton channel (F0 subunit), which is necessary for oxidative phosphorylation of ADP to ATP (energy production). The inhibition of ATP synthesis would also stop electron transport chain.
What is the most likely explanation to explain how ATP can be an inhibitor and a substrate of PFK?
Although ATP is one of the substrates of PFK-1, high concentration of ATP saturates the catalytic site. This increases the binding of ATP to the allosteric site, inhibiting the PFK-1. Increased ATP concentration, decreases glucose flux through glycolysis as the key enzyme, PFK-1, is inhibited.
What is the difference between nonactin and valinomycin?
Valinomycin is a neutral cyclic dodecadepsipeptide antibiotic having a 36-member ring, and nonactin is a neutral macrotetralide antibiotic with a 32-member ring [2,43-45]. Both are hydrophobic and partition strongly into the hydrocarbon region of the membrane. They also bind K + with some specificity.
What is the molecular geometry of valinomycin?
The circular structure is a macrocyclic molecule where 12 carbonyl oxygens face the inside of the structure where they chelate a single K +. The outside surface of valinomycin is coated with 9 hydrophobic side chains of D- and L-valine and L-hydroxyvaleric acid. The polar interior of valinomycin precisely fits one K +.
Is valinomycin a potassium ionophore?
Valinomycin was first recognized as a potassium ionophore by Bernard Pressman in the early 1960’s [31,32]. He reported that valinomycin, a known antibiotic, stimulated K+ uptake and H+ efflux from mitochondria.
How does valinomycin pass through the membrane?
Valinomycin, therefore, has an oily surface that readily dissolves in a membrane lipid bilayer, carrying K + across the membrane down its electrochemical gradient. Valinomycin was first recognized as a potassium ionophore by Bernard Pressman in the early 1960s [31,32].