Studies on Riboflavin Kinase and FAD Pyrophosphorylase

Abstract

1. Distribution of flavokinase and FAD-pyrophosphorylase in various organs and the cell fractionations were described.
2. Flavokinase and FAD-pyrophosphorylase were separated from the same starting tissue by DEAE-Sephadex column chromatography.
3. Several properties of the purified enzymes were investigated. The most effective metal ion, optimum pH, activation energy and Michaelis constant were determined.
4. Inhibition of flavin enzymes by D-araboflavin showed a competitive one which was distinctly observed on flavokinase and no effect was found on FAD-pyrophosphorylase. This would suggest that the inhibition of araboflavin occurred on the first phosphorylation step of free riboflavin in the body.