Ionophores (UPSC CMS)

An ionophore is a lipid-soluble molecule usually synthesized by microorganisms to transport ions across the lipid bilayer of the cell membrane.

The two broad classifications of ionophores are:

Chemical compounds (mobile ion carriers) that bind to a particular ion shielding its charge from the surrounding environment, and thus facilitating its crossing of the hydrophobic interior of the lipid membrane
Channel formers that introduce a hydrophilic pore into the membrane, allowing ions to pass through while avoiding contact with the membrane's hydrophobic interior

Ionophores disrupt the transmembrane ion concentration gradients required for the proper functioning and survival of microorganisms, and thus have antibiotic properties. They are produced naturally by a variety of microbes and act as a defense against competing microbes. Many antibiotics, particularly the macrolide antibiotics, are ionophores that exhibit high affinities for Na+ or K+. The structure of the sodium and potassium complexes of antibiotics have been repeatedly verified by X-ray crystallography.

Carrier ionophores

In laboratory research, ionophores are used to increase the permeability of biological membranes to certain ions. Additionally, some ionophores are used as antibiotics and/or as growth-enhancing feed additives for certain feed animals, such as cattle.

Some macrolide antibiotics which are use for cattles act as ionophores. Ionophore antibiotics are not used for human use.

Related MCQ in UPSC CMS

91. Some antibiotics act as ionophores which means that they
(a) interfere directly with bacterial cell wall synthesis
(b) increase cell membrane permeability to specific ions
(c) inhibit both transcription and translation
(d) inhibit electrophoretic separation of ions

Source: Wikipedia