Intramolecular electron transfer in the oxidation of amines by methylamine oxidase from Arthrobacter P1
Intramolecular electron transfer in the oxidation of amines by methylamine oxidase from Arthrobacter P1
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DOI：
10.1007/s007750050044
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发表时间：
1996-06-01
影响因子：
3
通讯作者：
Brown, DE
中科院分区：
文献类型：
--
作者：
Dooley, DM;Brown, DE
用温度跃变弛豫技术测定了甲胺氧化酶中Cu（II）-topa（NH_2）可逆箭Cu（I）-topa（SQ）平衡的分子内电子转移速率常数。在pH 7.0时，甲胺和苄胺的估计k（obs）= 150+/-30 s（-1）;假设在pH 7.0和296 K时平衡常数约为0.7-1，这将对应于前向电子转移速率常数k（ET）约为60-75 s（-1）。尽管比先前确定的豌豆幼苗胺氧化酶的k（ET）（约20000 s（-1））慢得多[5]，但稳态动力学测量确定k（ET）> k（cat）（约4-10 s（-1））。因此，Cu（I）-半醌状态是甲胺氧化酶周转中的可行中间体。
The intramolecular electron-transfer rate constant for the Cu(II)-topa(NH2) reversible arrow Cu(I)-topa(SQ) equilibrium in methylamine oxidase has been measured by temperature-jump relaxation techniques. At pH 7.0 the estimated k(obs) = 150+/-30 s(-1) for both methylamine and benzylamine; assuming the equilibrium constant is approximate to 0.7-1 at pH 7.0 and 296 K, this would correspond to a forward electron-transfer rate constant k(ET) approximate to 60-75 s(-1). Although substantially slower than the previously determined k(ET) approximate to 20000 s(-1) for pea seedling amine oxidase [5] steady-state kinetics measurements established that k(ET) > k(cat) approximate to 4-10 s(-1). Thus the Cu(I)-semiquinone state is a viable intermediate in methylamine oxidase turnover.