Some observations on the interaction of dopamine-β-hydroxylase and its natural inhibitors in the rat brain

Abstract

The difficulty of assaying dopamine-β-hydroxylase (DβH) (EC 1.14.17.1) has been circumvented by including N-ethylmaleimide (5 × 10−2 M) in the incubation mixture along with a small amount of Cu2+ (20–60 μM). Such a procedure ensures that the maximum DβH activity is assessed in all extracts. As a result, the absolute levels of DβH in various regions of the rat brain have been established. The DβH values obtained are higher by 40% in the hypothalamus and 20% in the cerebral cortex, spinal cord, and caudate nucleus than those previously reported. The mechanism of the synergic effect seen when N-ethylmaleimide and Cu2+ are combined is not presently understood.