[Interaction of the antitumor antibiotic olivomycin with Mg2+ ions]

The study on the mechanisms of olivomycin and olivin interaction with the magnesium ions showed that formation of the olivomycin complexes with Mg2+ involved 2 stages. At the first (rapid) stage Mg2+ is attached to keto-oxygen of the aglycone polycyclic part. At the second (slow) stage the complex is relaxed into the stable state with a more compact configuration. the equilibrium constants (Ce) of the main processes of olivomycin and olivin interaction with Mg2+ were determined. In the first case Ce = 3 . 10(3) M+1 and in the second case Ce = 1.6 . 10(2) M-1. It was shown that the geometric and optic characteristics of the complexes were consistently related: formation of the stable complex was accompanied by a 10-time decrease in the fluorescence quantum efficiency.