A new method for the determination of estrogen-2-hydroxylase activity

A new method is described for determining the activity of a monooxygenase, acting by specific hydroxylation at the 2- position of the aromatic ring of estrogenic compounds with the formation of catechol estrogens. The procedure is based on separation of the catechol estrogen product from the substrate by high performance reversed-phase chromatography with amperometric detection in a thin-layer flow-cell by electrooxidation at a graphite-paste anode. Due to the very high detector sensitivity for the enzymatically generated product and an uncomplicated overall performance, the method offers great advantages over the radioenzymatic assay described earlier.