Enzymatic hydroxylation of 6'-deoxychalcones with protein preparations from petals of Dahlia variabilis
1998
Wimmer, G. | Halbwirth, H. | Wurst, F. | Forkmann, G. | Stich, K.
Yellow colouration of Dahlia variabilis flowers is mainly based on isoliquiritigenin and butein 4'-malonylglucosides. Microsomal preparations from petals of the yellow strain 'Johann Nestroy' catalyse the enzymatic 3-hydroxylation of isoliquiritigenin to butein in the presence of NADPH. The reaction showed a pH optimum of 7.5, and was inhibited by p-hydroxymercuribenzoate and a number of cytochrome P450 specific inhibitors. These and further properties suggest that the 3-hydroxylation of isoliquiritigenin is mediated by a cytochrome P450-dependent monooxygenase. The apparent Km value for isoliquiritigenin was 50 micromolar.
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