Effects of riboflavin deficiency and realimentation on flavin enzymes of tissues.

This study was undertaken to determine how flavin enzymes are distributed in different tissues and their fate with riboflavin restriction of greater or lesser severity. Such a study might be expected to uncover differences in metabolic patterns of different tissues and to expose enzymatic defects which must underlie the functional deficits and physical changes of riboflavin deficiency. Tissues differ as much as 1Bfold in their concentrations of FAD1 and FMN (1) and probably, therefore, in their total content of flavin enzymes. Specific flavoproteins may vary even more from organ to organ. For the understanding of normal function it may be well to know more about the distribution of these specific enzymes. In this paper, concentrations of FAD and FMN and activities of xanthine oxidase, Dand Lamino acid oxidases, glycine and glycolic acid oxidases, and DPNH-oxidizing enzymes are reported for various normal and deficient rat tissues. The rates at which some of these enzymes decrease in liver and kidney during riboflavin deficiency and increase during realimentation are also given.