Biphasic Photolysis of Riboflavin. II. Effect of Gelatin on the Photolysis

Abstract

The photolysis of riboflavin in the presence of gelatin with a low-intensity light source was investigated. It was found that the time course of photolysis was triphasic. The first break in the time course was attributed to dissociation of dimeric riboflavin. The second break may result from a change of relative predominance between the reactive species, i. e., the singlet and triplet states of excited riboflavin. The changes of thermodynamic parameters are discussed from the viewpoint of riboflavin stability. The data suggest that gelatin promotes the photolysis of riboflavin via energy transfer from protein, though it has a stabilizing effect in the initial stage of irradiation.