Wimalasena K, Wimalasena D S
Department of Chemistry, Wichita State University, KS 67208.
Biochem Biophys Res Commun. 1991 Mar 29;175(3):920-7. doi: 10.1016/0006-291x(91)91653-t.
Dopamine beta-monooxygenase is shown to catalyze the oxidation of N,N,N',N'-tetramethyl-1,4-phenylenediamine (TMPD) to its cation radical in the presence of a regular substrate and molecular oxygen. The enzyme-mediated oxidation of TMPD is stoichiometrically coupled with the hydoxylation of the substrate to the corresponding enzymatic product. TMPD is kinetically well behaved as an alternate electron donor for the enzyme with a potency comparable to that of the most efficient electron donor, ascorbate. Dopamine beta-monooxygenase mediated oxidation of TMPD has been employed to design a convenient and sensitive spectrophotometric assay for the enzyme. The finding that TMPD is a well behaved facile alternate electron donor for dopamine beta-monooxygenase raises some interesting novel questions regarding the specificity and chemistry of the reduction site, which may have important implications on the reduction of active site coppers of the enzyme.
已表明多巴胺β-单加氧酶在存在常规底物和分子氧的情况下，能催化N,N,N',N'-四甲基-1,4-苯二胺（TMPD）氧化为其阳离子自由基。酶介导的TMPD氧化与底物羟基化为相应的酶促产物在化学计量上偶联。TMPD在动力学上表现良好，作为该酶的替代电子供体，其效力与最有效的电子供体抗坏血酸相当。多巴胺β-单加氧酶介导的TMPD氧化已被用于设计一种方便且灵敏的该酶的分光光度测定法。TMPD是多巴胺β-单加氧酶行为良好的便捷替代电子供体这一发现，引发了一些关于还原位点的特异性和化学性质的有趣新问题，这可能对该酶活性位点铜的还原具有重要意义。
