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Dopamine beta-monooxygenase, also known as dopamine beta-hydroxylase, is an enzyme that in humans is encoded by the DBH gene. Dopamine beta-monooxygenase catalyzes the chemical reaction: The 3 substrates of this enzyme are 3,4-dihydroxyphenethylamine, ascorbate, and O2, whereas its 3 products are noradrenaline, dehydroascorbate, and H2O. DBH is a 290 kDa copper-containing oxygenase consisting of four identical subunits, and its activity requires ascorbate as a cofactor. It is the only enzyme involved in the synthesis of small-molecule neurotransmitters that is membrane-bound, making norepinephrine the only transmitter synthesized inside vesicles. It is expressed in noradrenergic nerve terminals of the central and peripheral nervous systems, as well as in chromaffin cells of the adrenal medulla. == Mechanism of catalysis == Based on the observations of what happens when there's no substrate, or oxygen, the following steps seem to constitute the hydroxylation reaction. Although details of DBH mechanism are yet to be confirmed, DBH is homologous to another enzyme, peptidylglycine α-hydroxylating monooxygenase (PHM). Because DBH and PHM share similar structures, it is possible to model DBH mechanism based on what is known about PHM mechanism. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dopamine beta-monooxygenase」の詳細全文を読む スポンサード リンク
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