Spectroscopic studies on the mechanism of the topa quinone generation in bacterial monoamine oxidase.
Spectroscopic studies on the mechanism of the topa quinone generation in bacterial monoamine oxidase.
复制标题
细菌单胺氧化酶中托巴醌生成机制的光谱研究。
作者：
R. Matsuzaki;Shinnichiro Suzuki;K. Yamaguchi;Toshio Fukui;K. Tanizawa
利用电子顺磁共振（EPR）、圆二色性（CD）和光学吸收光谱研究了球状节杆菌重组苯乙胺氧化酶中产生6-羟多巴（topa）醌辅助因子的铜依赖自氧化过程。根据严格厌氧条件下观察到的光谱特征推断，铜离子结合到铜/托帕醌无活性酶上，首先还原为Cu(I)。铜(I)也可以用铜(I)特异性螯合剂——二磺酸盐进行化学检测。引入一定量的氧气就会形成顺磁性物质（g = 2.004），这种物质在几到10分钟内是稳定的，但在加入足够的氧气后就会迅速消失。引人注目的是，有机自由基的超精细EPR结构几乎与在含铜/托帕醌的活性酶厌氧还原底物中观察到的托帕半喹啉胺相同。在完全好氧条件下生成具有典型光吸收和CD带的topa醌的同时，结合铜最终表现出典型的非蓝色II型铜（II）的EPR信号和700 nm左右的光吸收，700 nm以上的负CD。这些光谱变化在Cu（II）与Tyr382- b> Phe突变酶结合时都没有引起，这表明topa醌的前体Tyr382参与了结合铜的初始还原，并作为瞬时形成的半醌自由基的来源。假体铜离子通过改变其氧化还原状态，在酪基酚环的氧化修饰中起着至关重要的作用，从而产生托帕醌。
Electron paramagnetic resonance (EPR), circular dichroism (CD), and optical absorption spectroscopies have been used to investigate the copper-dependent autoxidation process generating the 6-hydroxydopa (topa) quinone cofactor in the recombinant phenethylamine oxidase from Arthrobacter globiformis. The cupric ion bound to the copper/topa quinone-less, inactive enzyme is first reduced to Cu(I), as inferred from the spectroscopic features observed under strictly anaerobic conditions. Cu(I) is also detectable chemically with a Cu(I)-specific chelating agent, bathocuproinedisulfonate. Introduction of a limited amount of oxygen then leads to the formation of a paramagnetic species (g = 2.004) that is stable for over several to 10 min but vanishes swiftly upon addition of sufficient oxygen. Strikingly, the hyperfine EPR structure of the organic radical is almost identical with that of the topa semiquinolamine observed in the copper/topa quinone-containing, active enzyme anaerobically reduced with substrate. Concomitant with the generation of topa quinone exhibiting characteristic optical absorption and CD bands under fully aerobic conditions, the bound copper finally shows EPR signals typical of nonblue type II Cu(II) and optical absorption around 700 nm with negative CD above 700 nm. None of these spectral changes are evoked in the binding of Cu(II) to the Tyr382-->Phe mutant enzyme, indicating that the precursor Tyr382 to topa quinone participates in the initial reduction of bound copper and serves as the origin of the transiently formed semiquinone radical. The prosthetic cupric ion plays an essential role, by changing its redox state, in the oxidative modification of the tyrosyl phenol ring, leading to topa quinone.
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哺乳动物细胞和血清铜胺氧化酶的一级结构。
DOI：
--
发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Mu,D;Medzihradszky,KF;Adams,GW;Mayer,P;Hines,WM;Burlingame,AL;Smith,AJ;Cai,D;Klinman,JP
通讯作者：
Klinman,JP
豌豆苗胺氧化酶活性位点铜和托帕醌之间的分子内电子转移速率。
DOI：
--
发表时间：
1993
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Turowski,PN;McGuirl,MA;Dooley,DM
通讯作者：
Dooley,DM
影响因子：
2.9
作者：
CAI, DY;KLINMAN, JP
通讯作者：
KLINMAN, JP
影响因子：
2.9
作者：
DEFELIPPIS, MR;MURTHY, CP;KLAPPER, MH
通讯作者：
KLAPPER, MH
酪氨酸密码子对应于铜胺氧化酶活性位点的托帕醌。
DOI：
--
发表时间：
1992
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Mu,D;Janes,SM;Smith,AJ;Brown,DE;Dooley,DM;Klinman,JP
通讯作者：
Klinman,JP