Dopamine-β-hydroxylase-Induced Changes in the Electrical Conductance of Bimolecular Lipid Membranes

Dopamine-β-hydroxylase (DBH), an enzyme that catalyzes the conversion of dopamine (DA) to norepinephrine (NE) in adrenal medullary chromaffin granules, increases the electrical conductance of bimolecular lipid membranes. The conductance increase requires both DA and Ca²⁺ and occurs in discrete steps. The conductance, which increases as the square of the DBH concentration, is nonselective for cations over anions and requires the native conformation of DBH. NE cannot replace DA.