Superoxide mediated chlorophyll allomerization in a dimethyl sulphoxide-water mixture.

The interaction of chlorophyll a with superoxide anion was studied in an alkaline DMSO-water system. It was found that O2(-.), directly or via HO2., produces the chlorophyll enolate-ion (Molish's intermediate) that is oxidized to Mg-chlorine(s). The allomerization reaction was found to be inhibited by superoxide dismutase. A possible participation of oxygen radicals in chlorophyll degradation in plants is discussed.