Factors Affecting Levels of the Flavin Coenzymes in Higher Plants

The activities and catalytic properties of the enzymes related with the biosynthesis and biodegradation of riboflavin and flavin coenzymes in green leaves were investigated.1) The activities of FMN- and FAD-biosynthesizing enzymes are by far surpassed by those of hydrolyzing enzymes.2) Factors affecting the biosynthesis and hydrolysis of flavin coenzymes in vivo, such as pH value, substrate concentration, and adenine nucleotides concentrations, are enumerated.3) FAD bound to the protein does not receive the action of nucleotide pyrophosphatase.4) The possibility for controlling the level of flavin coenzymes in vivo is discussed basing on the facts revealed.