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PHOTOCHEMICAL DEGRADATION OF FLAVINS‐IV. STUDIES OF THE ANAEROBIC PHOTOLYSIS OF RIBOFLAVIN *
Author(s) -
Song PillSoon,
Metzler David E.
Publication year - 1967
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1967.tb08735.x
Subject(s) - chemistry , photochemistry , flavin group , riboflavin , photobleaching , photodissociation , quenching (fluorescence) , singlet oxygen , triplet state , fluorescence , quantum yield , photodegradation , kinetics , oxygen , molecule , organic chemistry , catalysis , photocatalysis , biochemistry , physics , quantum mechanics , enzyme
A variety of substances which quench the fluorescence of riboflavin decrease the rate of anaerobic photobleaching (photolysis) of the flavin at concentrations which have little effect on the fluorescence. A semi‐quantitative estimate of the yield of various products of photolysis using thin layer chromatography and autoradiography with C 14 ‐labelled riboflavin shows that at least ten radioactive products are formed. Whereas the yield of most of these is decreased by low concentrations of quenchers, such as phenol, some are decreased only at quencher concentrations high enough to decrease the fluorescence significantly. The effects of quenchers on the phosphorescence and ESR signal induced by light were also observed. It is concluded that lumichrome arises, in part, from degradation of the excited singlet state, but that 9‐formylmethylflavin and other products arise through the triplet state. A major product of anaerobic photolysis is a substance moving just ahead of riboflavin on chromatograms and which, like 9‐formylmethylflavin, is destroyed by treatment with sodium hydroxide. Effects of varying the nature of the solvent, the flavin structure and the pH are reported, and the kinetics of processes involved in the primary photochemical acts and in quenching are discussed.