FREE-RADICAL FORMATION DURING PHOTOOXIDATION OF BACTERIOVIRIDIN IN MONOMERIC AND AGGREGATED STATE

  • 1 January 1977
    • journal article
    • research article
    • Vol. 22  (5) , 780-788
Abstract
ESR study of photooxidation of [Chloribium limicola] bacterioviridin in polar and non-polar organic solvents containing monomeric and aggregated forms of the pigment was carried out. Light-induced formation of free radicals proceeded during photooxidation of bacterioviridin with O2. These free radicals were similar by the ESR-signal parameters (G-factor value and the line width) to the cation-radicals initiated during photooxidation of the pigment with p-benzoquinone and at the same time differing in kinetics and temperature relationship. A small yield of radical products in the presence of O2 is observed in non-polar solvents where bacterioviridin forms the aggregated forms with the absorption maxima of 680 and 720 nm. The study of the kinetics of photoformation of radicals within the temperature range 20.degree.-110.degree. C revealed different stages corresponding to the oxidation of the long wave and short wave forms of bacterioviridin, photooxidation of the long wave aggregated form being the 1st stage of photoprocess. Aggregations apparently contribute to the stabilization of the primary reversible products of bacterioviridin photooxidation having the nature of free radicals.

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