P-450-DEPENDENT OXIDATIVE REARRANGEMENT IN ISOFLAVONE BIOSYNTHESIS: RECONSTITUTION OF P-450 AND NADPH:P-450 REDUCTASE

Article abstract of DOI:10.1016/S0040-4020(01)86489-9

The reaction mechanism of oxidative rearrangement in the conversion of liquiritigenin, a flavanone, into 2,7,4'-trihydroxyisoflavanone was studied in elicitor-challenged Pueraria lobata cell cultures.The involvement of cytochrome P-450 in the reaction, hydroxylation associated with 1,2-aryl migration, was proved previously by the inhibition experiments with carbon monoxide and P-450 inhibitors.In order to obtain rigorous evidence proving that the enzyme is a P-450, a reconstitution experiment was performed with solubilized cytochrome P-450 and NADPH:cytochrome P-450 reductase fractions.During these studies we noticed that various biosynthetic reactions can be interpreted as P-450-mediated reactions associated with migration or bond cleavage.Ring contraction of 7-hydroxy-kaurenoic acid in gibberellin biosynthesis, the formation of a furan ring in furanocoumarin biosynthesis and several rearrangement reactions in steroid metabolism are discussed as examples of P-450 reactions associated with migration or bond cleavage.