Colicin E1 is purified (8.6-fold to Specific Activity of 1.5 x 10units/mg) from E.coli JC411 by salt extraction of extracellular-bound colicin followed by (NH4)2SO4 (40-60% saturation) fractionation and ion-exchange chromatography on a DEAE-Sephadex A 50 column, and then by CM-Sephadex column chromatography [Schwartz & Helinski J Biol Chem 246 6318 1971].
