2.B.6 The Ionomycin (Ionomycin) Family Ionomycin is an ionophoric antibiotic synthesized by Streptomyces conglobatus sp. Treja. It functions as an antibiotic against many Gram-positive bacteria. The 1:1 Ca²⁺ complex has the formula C₄₁H₇₀O₉Ca²⁺ (MW = 747). It is a lipid soluble divalent cation-specific ionophore that transports divalent cations across biological and artificial membranes by a carrier-type mechanism. It exhibits cation selectivity in the order: Pb²⁺ > Cd²⁺ > Zn²⁺ > Mn²⁺ > Ca²⁺ > Cu²⁺ > Co²⁺ > Ni²⁺ > Sr^2+. The generalized reaction catalyzed by ionomycin is: C²⁺(out)C²⁺(in). (C²⁺ = divalent cation)
References:
Bennett, J.P., S. Cockcroft and B.D.Gomperts. Ionomycin stimulates mast cell histamine secretion by forming a lipid-soluble calcium complex. Nature 282: 851-853.
Erdahl, W.L., C.J. Chapman, R.W. Taylor, and D.R. Pfeiffer. (2000). Ionomycin, a carboxylic acid ionophore, transports Pb(2+) with high selectivity. J. Biol. Chem. 275: 7071-7079.
Liu, W.C., D.S. Slusarchyk, G. Astle, W.H. Trejo, N.E. Brown and E. Meyers (1978). Ionomycin, a new polyether antibiotic. J. Antibiot. 9: 815-819.
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TC#	Name	Organismal Type	Example