Oligomycin A complex structures with some divalent metal cations studied by ESI MS and PM5 semiempirical methods

Abstract

The ability of Oligomycin A (OLA) to form complexes with monovalent cations was studied by the ESI mass spectrometry and PM5 semiempirical method. At low cone voltage values the ESI MS spectra indicate that OLA formes stable 1:1 complexes with Mg 2+, Ca 2+, Sr 2+, Ba 2+, Zn 2+ divalent cations irrespective of the stoichiometry. With increasing cone voltages the formation of the [OLA + M + (ClO 4 or Cl)] + complexes was preferred. This process occurred simultaneously with the formation of fragmentary metal cation complexes with the exception of Pb 2+ ions which does not form complexes with OLA molecule. PM5 semiempirical calculations allowed the visualizations of all structures of (OLA + M) 2+ and [OLA + M + (ClO 4or Cl)] + complexes as well as the fragmentary cations.