title: Conformational change on calcium binding by the lipopeptide antibiotic amphomycin. A C.D. and monolayer study.
abstract: The acidic linear lipopeptide amphomycin is a calcium dependent antibiotic which is thought to bind to carrier lipids such as dolichol monophosphate. The actual role of Ca++ is not definitely established and in this article we have examined the peptides interactions with a range of divalent cations. By CD we have shown that a conformational change is induced by Ca++, Sr++ and Ba++ but not by Mg++, Zn++, Cd++ or Gd+++. Monolayer studies show a decrease in molecular area and an increase in film stability when the subphase contains Ca++. The ensemble of results provides preliminary evidence for the formation of a beta hairpin structure on ion binding (Ka (Ca++) = 2.4 x 10(3)M-1) which could enhance amphomycin's bilayer solubility.
authors.affiliation: Centre de Biophysique Moléculaire, CNRS and the Université d'Orléans, France.
authors.forename: J H
authors.initials: JH
authors.lastname: Lakey
authors.forename: R
authors.initials: R
authors.lastname: Maget-Dana
authors.forename: M
authors.initials: M
authors.lastname: Ptak
mesh_terms: D000900:Anti-Bacterial Agents; D001464:Barium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002122:Calcium Chloride / Q000494:pharmacology; D002413:Cations, Divalent; D002942:Circular Dichroism; D008051:Lipid Bilayers / Q000378:metabolism; D055666:Lipopeptides; D009842:Oligopeptides / Q000378:metabolism; D011487:Protein Conformation / Q000187:drug effects; D012996:Solutions; D013324:Strontium / Q000378:metabolism; D013499:Surface Properties; D013816:Thermodynamics; D014867:Water
chemical_list: D000900:Anti-Bacterial Agents; D002413:Cations, Divalent; D008051:Lipid Bilayers; D055666:Lipopeptides; D009842:Oligopeptides; D012996:Solutions; D014867:Water; D001464:Barium; C004423:amphomycin; D002122:Calcium Chloride; D002118:Calcium; D013324:Strontium