title: Purification and molecular properties of a new colicin.
abstract: The process of isolation and purification of a new colicin isolated from a Citrobacter strain is described. Escherichia coli sensitive cells are protected by vitamin B12 from the action of this bacteriocin; this suggests that it belongs to the E group of colicins. Therefore, we have called it colicin E4. It has a molecular weight of 56 000 and two molecular forms of isoelectric points 9.4 and 8.2 are separated in electrofocusing on polyacrylamide gels. It has a sedimentation coefficient of 3.4 S and the absorption coefficient A1(280%) nm is 6.23 cm(-1). Using an antibody raised against pure colicin E4, no cross-reaction was detected against colicins A, E1 or K. The physiological effect of colicin E4 on sensitive cells is very similar to that of colicins E1, K or I which disrupt the energized membrane state.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002954:Citrobacter / Q000378:metabolism; D003087:Colicins / Q000096:biosynthesis / Q000276:immunology / Q000302:isolation & purification*; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli; D007700:Kinetics; D011392:Proline / Q000378:metabolism
chemical_list: D000596:Amino Acids; D003087:Colicins; D011392:Proline