Flavin Sensitized Photoreactions: Effects of 3-( p -Chlorophenyl)-1,1-Dimethylurea

Abstract

Photooxidation reactions, which were inhibited by high concentrations of oxygen, were affected by the addition of 3-(p-chlorophenyl)-1,1-dimethylurea (CMU), but the response varied with the substrate being oxidized. With ascorbic acid and 2,3-diketogulonic acid, CMU reversed the inhibition caused by high concentrations of oxygen. With ethylenediaminetetraacetic acid (EDTA), tetraethylene tetramine, or Mn⁺⁺ as reductant, CMU itself inhibited the reactions. The photoreduction of flavins by EDTA and the bleaching of flavin mononucleotide under anaerobic conditions were also inhibited by CMU. Corresponding photoreactions sensitized by phthaleine dyes or methylene blue were completely insensitive to CMU. This compound therefore seems to change specifically the reactivity of excited flavin molecules.