An investigation was made of the photoreduction of indigo carmine dye and flavin mononucleotide (FMN) by an illuminated sugar beet leaf homogenate in the presence of 2,6-dichlorophenolindophenol dye (DPIP) and ascorbic acid. DPIP and ascorbate were absolutely required for the reaction. Reconstitution experiments indicated a requirement for a heat-labile factor present in the supernatant fluid following centrifugation of the leaf homogenate. This factor activated the photoreduction of indigo carmine more than 20 times. The photoreduction of FMN was activated 2 times by this factor. Studies on the stoichiometry of indigo carmine photoreduction revealed that one mole of ascorbate was photooxidized for each mole of indigo carmine photoreduced. It is postulated that the DPIP-ascorbate couple serves to prevent reoxidation of reduced indigo carmine by either reacting with the photochemical [OH] system or by depleting the O_2 content of the solution.
College and Department
Chemistry and Biochemistry
BYU ScholarsArchive Citation
Hobbs, M. Odell, "The photoreduction of indigo carmine flavin mononucleotide and diphosphopyridine nucleotide, by illuminated chloroplasts" (1958). Theses and Dissertations. 8230.