Production, purification, and characterization of excitability-inducing molecule.

Excitability-inducing molecule (EIM) is a high molecular weight polymeric protein. It is a channel-forming ionophore which can induce action potential in lipid bilayers and lyse red blood cells. It is also a potent mitogen for mouse B lymphocytes. EIM is produced and secreted into a chemically defined medium during the early growth period by Enterobacter cloacae ATCC 961. It is now 6000-fold purified as compared to the original egg white EIM. Production of the active material requires calcium ion. EIM contains 10 to 20% lipid by weight which is primarily composed of fatty acids, with an unsaturated 18-carbon chain. Amino acid analysis shows 18 common amino acids. The maximum specific activity of 18 common amino acids. The maximum specific activity of EIM is associated with the molecular weight of 3.6 x 10(5).