An ionophore is a lipid-soluble molecule usually synthesized by microorganisms to transport ions across the lipid bilayer of the cell membrane. There are two broad classifications of ionophores.

1) Small molecules (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.

2) 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 transmembrane ion concentration gradients, required for the proper functioning and survival of microorganisms, and thus have antibiotic properties. They are produced naturally by certain microbes and act as a defense against competing microbes.

In the lab, ionophores are used by scientists to increase the permeability of biological membranes to certain ions. Additionally, some ionophores are used as antibiotics.

1. Ionomycin (Ca++)
2. Beauvericin (Ca++, Ba++)
3. Nonactin (Amonium ionophore I)
4. Nigericin (K+, H+, Pb++)
5. CCCP
6. Valinomycin
7. Crown ether
8. Chlorogenic acid
9. Calixarene
10. Calcimycine ( A23187 )
11. Proton ionophore II ( 4-Nonadecylpyridine )
12. Proton ionophore III ( N,N-Dioctadecylmethylamine )

Ionophore