Flavonoid 3-hydroxylase has been demonstrated using freshly peeled intact aleurone tissue as the source of the enzyme in the reaction mixture. The reaction requires a-ketoglutarate, ascorbic acid and Fe2+. Eriodictyol serves as a substrate, resulting in the formation of dihydroquercetin, which can be chemically oxidized to quercetin. Quercetin has been identified by thin layer and high performance liquid chromatography. Thus far it has not been possible to obtain catalytic activity free of the intact aleurone tissue, nor has it been possible thus far to obtain any information as to what gene(s) influence hydroxylation.
Russell L. Larson
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