[Chalcone-flavanone isomerase activity and accumulation of phenylpropanoid compounds in anthers]

Chalcone-flavanone isomerase from the anthers of Lilium candidum and Tulipa cv. "Apeldoorn" exhibits a distinct substrate specificity. The enzyme catalyses only the isomerization of 2',4,4',6'-tetrahydroxychalcone, whereas it is not active with 2',4,4'-trihydroxychalcone.During the final stage in the development of the anthers, differing isomerase activities were observed. Maximum enzyme activity was measured at a point when the concentration of chalcones was decreasing rapidly and the concentration of flavonols was increasing. These findings strongly support the suggestion that the isomerase plays an important role in flavonoid metabolism.