Valinomycin

A naturally occurring dodecadepsipeptide antibiotic

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Structure of valinomycin

Valinomycin is a naturally occurring dodecadepsipeptide antibiotic and ionophore, produced by several species of Streptomyces. It is notable for its ability to selectively transport potassium ions across lipid membranes.

Structure

Valinomycin is a cyclic peptide composed of twelve alternating amino acids and ester groups. The structure includes three repeating units of L-valine, D-alpha-hydroxyisovaleric acid, D-valine, and L-lactic acid. This unique arrangement allows valinomycin to form a complex with potassium ions, facilitating their transport across cell membranes.

Function

Valinomycin functions as an ionophore, specifically facilitating the transport of potassium ions (K_) across lipid bilayers. It achieves this by forming a stable complex with the potassium ion, effectively shielding it from the hydrophobic environment of the lipid membrane. This property makes valinomycin a useful tool in studies of membrane potential and ion transport.

Biological Activity

Valinomycin exhibits antibiotic properties due to its ability to disrupt ion gradients across bacterial cell membranes, leading to cell death. It is particularly effective against Gram-positive bacteria. However, its use as an antibiotic is limited due to its toxicity to eukaryotic cells.

Applications

In addition to its role in biological research, valinomycin is used in biochemistry and biophysics to study ion transport and membrane dynamics. It is also employed in analytical chemistry for the selective detection of potassium ions in various samples.

Safety and Toxicity

Valinomycin is highly toxic to eukaryotic cells, including human cells, due to its ability to disrupt cellular ion homeostasis. It is classified as a hazardous substance and must be handled with care in laboratory settings.

Related pages

• Ionophore
• Streptomyces
• Antibiotic