STUDIES ON A MATERIAL WHICH INDUCES ELECTRICAL EXCITABILITY IN BIMOLECULAR LIPID MEMBRANES .I. PRODUCTION ISOLATION GROSS IDENTIFICATION AND ASSAY

This report constitutes the first part of an investigation into the nature of the material which induces electrical excitability in experimental bimolecular lipid membranes. The excitability-inducing material (EIM) is released upon growth of Aerobacter cloacae ATCC 961 in a defined medium containing only low molecular weight substances. It has been isolated by adsorption on Kieselgel and subsequent elution with 1% ammonia solution. By TEAE-cellulose column chromatography of EIM solution, protein and RNA moieties, the only detectable components of EIM, have been separated. The separation of moieties results in loss of activity. Partial reactivation can be obtained by mixing 1% solutions of the protein and RNA. This reactivation does not occur when 0.1% solutions (or lower) are mixed. Both moieties obtained by TEAE-cellulose column chromatography shows gross homogeneity by electrophoretic and sedimentation studies. The basic properties of the protein moiety, not evident with total EIM, become apparent after its separation from RNA. The chemical chromatographic and electrophoretic studies reported in this paper raise the possibility that a ribonucleoprotein complex constitutes the functional entity of the material. The paper also presents standardization of the EIM activity assay. © 1968.