Abstract
Dihydropteroate-synthesizing enzyme was found in 25 to 45% saturated fraction with ammonium sulfate of the extracts from pea seedlings, and some properties of the enzyme were investigated. The optimum pH for the enzyme activity was found to be 8.5 to 9.0 under the experimental conditions. In the enzyme reaction, Mg2+ was the most effective as cofactor, and the effect could partially be replaced by Mn2+, whereas divalent heavy metal ions inhibited the enzyme activity. This enzyme was also inhibited by p-chloromercuribenzoate. The Michaelis constant for 2-amino-4-hydroxy-6-pyrophosphorylmethyldihydropteridine was found to be 7.1×10-5 M. It has been suggested that the enzyme reaction proceeds stoichiometrically as shown in Reaction (a), and the reaction is reversible.
