DBH also known as dopamine beta hydroxylase that catalyzes the chemical reaction. DBH belongs to the family of oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with reduced ascorbate as one donor, and incorporation of one ato of oxygen into the other donor. Recombinant human DBH, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.