title: [Comparison of the lytic effect of gramicidin S and its derivatives on Bacillus megaterium and Micrococcus lysodeikticus protoplasts].
abstract: Essential differences were found between the lytic action of gramicidin S. on Bacillus megaterium protoplasts and that on Micrococcus lysodeikticus protoplasts. When protoplasts were suspended in a sucrose solution in phosphate buffer, the lytic activity of gramicidin S toward B. megaterium protoplasts increased with a rise in the antibiotic concentration; the lytic action of gramicidin S on M. lysodeikticus protoplasts was characterized by a complex concentration dependence. Gramicidin S derivatives lacking basic properties since the amino groups of their ornithine residues were either substituted with urea residues (carbamoyl gramicidin) of acetylated (diacetyl gramicidin) showed a high lytic activity toward the both bacterial species. In contrast to gramicidin S, the derivatives virtually did not change the permeability of cytoplasmic membranes when they acted on intact cells. In the absence of phosphates (when protoplasts were suspended in an aqueous sucrose solution), the lytic activity of gramicidin S decreased while carbamoyl gramicidin and diacetyl gramicidin still were capable of causing lysis of M. lysodeikticus protoplasts though not of B. megaterium protoplasts.
mesh_terms: D001410:Bacillus megaterium / Q000187:drug effects*; D001433:Bacteriolysis / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006096:Gramicidin / Q000494:pharmacology*; D008837:Micrococcus / Q000187:drug effects*; D011523:Protoplasts / Q000187:drug effects*; D013329:Structure-Activity Relationship
chemical_list: D006096:Gramicidin
vernacular_title: Sravnenie liticheskogo deĭstviia gramitsidina S i ego proizvodnykh na protoplasty Bacillus megaterium i Micrococcus lysodeikticus.