Spectral Studies of the Photobleaching of Riboflavin Phosphate

摘要

The spectral changes during photobleaching of riboflavin phosphate (Rf) in neutral solution was studied, both in oxygen free solutions, in presence of small amounts of oxygen, in air saturated solutions, and in presence of hydrogen peroxide. After anaerobic photolysis, aeration, and extraction of lumichrome (Lc) the solution contains an alkali sensitive and extremely light sensitive compound, deuteroflavin (Df). It was proved that these properties can not be due to hydrogen peroxide. The destruction of Rf takes place during the illumination and not during the aeration. After an initial build-up period, the anaerobic photolysis is a steady state process with regard to leuco-deuteroflavin (H sub 2 Df). Small amounts of oxygen increase the yield of Lc and decrease the concentration of H sub 2 Df. Aerobic photolysis leads to Lc and a compound with an absorption macimum at 400 millimicrons. Similar results are obtained in presence of H sub 2 O sub 2. Previous observations regarding the decrease in the quantum yield during the course of the anaerobic photobleaching, and the buffer effect, are confirmed, although not quantitatively. The results are compared with those from experiments with 10 mM EDTA.