title: X-ray structures of two forms of the antibiotic oligomycin A: an inhibitor of ATP synthase.
abstract: BACKGROUND
  Corrections to the chemical and x-ray structures of two forms of the antibiotic oligomycin A are presented: the original and best known, form (E), from Streptomyces diastatochromogenes, and a new form (C) from Streptomyces diastaticus.
  
  
  METHODS
  The crystal structures are isomorphous, crystallizing in space group P212121, with Z = 4[C45H73O11.CH3OH] per unit cell. Oligomycin A(E) refined with R1 = 0.0734, using Cu Kα x-radiation; and for Oligomycin A(C) R1 = 0.0651 using Mo Kα x-radiation.
  
  
  CONCLUSIONS
  Serious corrections to the previously published structure of oligomycin A(C) are discussed and implemented. As a supplementary study geometry optimization of side group R4 of oligomycin A(E) was undertaken and achieved by energy minimization. These additional results clearly confirm the delocalization in this region observed in both x-ray structures. This result is contrary to the generally accepted formulation. Knowledge of the correct structures is important to those involved in the study and applications of the pharmacological and biological properties of these materials.
authors.affiliation: School of Crystallography, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK. rex.palmer@btinternet.com
authors.forename: Rex A
authors.initials: RA
authors.lastname: Palmer
authors.forename: Mark
authors.initials: M
authors.lastname: Ladd
authors.forename: Brendan
authors.initials: B
authors.lastname: Howlin
authors.forename: David R
authors.initials: DR
authors.lastname: Lisgarten
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry*; D006860:Hydrogen Bonding; D025261:Mitochondrial Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008968:Molecular Conformation; D009840:Oligomycins / Q000737:chemistry*; D013302:Streptomyces / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004791:Enzyme Inhibitors; D009840:Oligomycins; C031004:oligomycin A; D025261:Mitochondrial Proton-Translocating ATPases