title: Polymyxin B and polymyxin B nonapeptide alter cytoplasmic membrane permeability in Escherichia coli.
abstract: The effects of polymyxin B and polymyxin B nonapeptide (PMBN) on the permeability of the Escherichia coli cytoplasmic membrane were investigated. Both compounds caused loss of free amino acids, uracil and K+ from E. coli. The rates of loss promoted by polymyxin B were one and a half to two-fold greater than those caused by PMBN. Although PMBN mediated loss of low molecular weight substances from E. coli, it was not bactericidal. In contrast, polymyxin B treated E. coli lysed and rapidly lost viability. We suggest that the bactericidal activity of polymyxin B may be related to its previously reported ability to release cytoplasmic proteins from bacteria.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism; D011112:Polymyxin B / Q000031:analogs & derivatives / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D014498:Uracil / Q000378:metabolism
chemical_list: D000596:Amino Acids; D011113:Polymyxins; D014498:Uracil; C038934:polymyxin B nonapeptide; D011112:Polymyxin B; D011188:Potassium