Steady-state kinetic analysis of the quinoprotein methylamine dehydrogenase from Paracoccus denitrificans.
Steady-state kinetic analysis of the quinoprotein methylamine dehydrogenase from Paracoccus denitrificans.
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脱氮副球菌的醌蛋白甲胺脱氢酶的稳态动力学分析。
DOI：
10.1042/bj2610107
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Davidson,VL
中科院分区：
文献类型：
--
作者：
Davidson,VL
对甲胺和吩嗪硫酸乙酯 (PES) 与脱氮副球菌的醌蛋白甲胺脱氢酶的反应进行了稳态动力学分析。使用甲胺和 PES 作为不同浓度底物的实验产生了一系列平行倒数图，并且当这些底物的浓度以恒定比例变化时，获得了初始速度对 PES 浓度的线性倒数图。使用四种不同的正烷基胺获得了几乎相同的 PES V/Km 值。这些数据表明该反应通过乒乓类型的机制进行。该酶与多种正烷基胺反应，但不与仲胺、叔胺或芳香胺或氨基酸反应。底物特异性主要由特定胺所表现出的 Km 值决定。以氘化甲胺为底物观察到氘动力学同位素效应。该酶对 V 的最适 pH 值为 7.5。该酶的吡咯并喹啉醌辅基的吸收光谱也受到大于 7.5 的 pH 值的影响。该酶对离子强度的变化相对不敏感，在 10°C 至 50°C 的温度范围内表现出线性阿伦尼乌斯图，活化能为 46 kJ/mol (11 kcal/mol)。
A steady-state kinetic analysis was performed of the reaction of methylamine and phenazine ethosulphate (PES) with the quinoprotein methylamine dehydrogenase from Paracoccus denitrificans. Experiments with methylamine and PES as varied-concentration substrates produced a series of parallel reciprocal plots, and when the concentrations of these substrates were varied in a constant ratio a linear reciprocal plot of initial velocity against PES concentration was obtained. Nearly identical values of V/Km of PES were obtained with four different n-alkylamines. These data suggest that this reaction proceeds by a ping-pong type of mechanism. The enzyme reacted with a variety of n-alkylamines but not with secondary, tertiary or aromatic amines or amino acids. The substrate specificity was dictated primarily by the Km value exhibited by the particular amine. A deuterium kinetic isotope effect was observed with deuterated methylamine as a substrate. The enzyme exhibited a pH optimum for V at pH 7.5. The absorbance spectrum of the pyrroloquinoline quinone prosthetic group of this enzyme was also effected by pH at values greater than 7.5. The enzyme was relatively insensitive to changes in ionic strength, and exhibited a linear Arrhenius plot over a range of temperatures from 10 degrees C to 50 degrees C with an energy of activation 46 kJ/mol (11 kcal/mol).