Multistep, eight-electron oxidation catalyzed by the cofactorless oxidase, PqqC: identification of chemical intermediates and their dependence on molecular oxygen.
Multistep, eight-electron oxidation catalyzed by the cofactorless oxidase, PqqC: identification of chemical intermediates and their dependence on molecular oxygen.
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DOI：
10.1021/bi4003315
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发表时间：
2013-07-09
期刊：
影响因子：
2.9
通讯作者：
Klinman, Judith P.
中科院分区：
文献类型：
--
作者：
Bonnot, Florence;Iavarone, Anthony T.;Klinman, Judith P.
原核辅助因子PQQ生物合成的最后一步由PqqC催化，PqqC是一种无辅助因子的氧化酶，它会导致环闭合并对底物进行全面的8电子氧化。为了将中间体的结构与之前观察到的UV/Vis特征联系起来，对反应混合物进行了随时间的酸猝灭和随后的HPLC分离和质谱分析。该反应由四步氧化组成：三步用O2作为双电子受体，第四步用过氧化氢（H2O2）。中间体的化学性质、反应的化学计量以及它们对氧浓度的依赖表明，第三次氧化使用前一步的产物H2O2生成水。最后一个氧化步骤也可以单独研究，它是O2与被困在活性位点的PQQH2之间的反应。这种氧化比PQQH2在溶液中的再氧化慢约10倍。从四个氧化步骤的顺序和它们对O2浓度的敏感性来看，我们提出了一个随着酶的催化循环而逐渐关闭活性位点的方法。
The final step of the biosynthesis of the prokaryotic cofactor, PQQ, is catalyzed by PqqC, a cofactorless oxidase that brings about a ring closure and overall eight-electron oxidation of its substrate. Time-dependent acid quenching and subsequent HPLC separation and mass spectrometric analyses of reaction mixtures were performed in order to correlate the structures of intermediates with previously observed UV/Vis signatures. The reaction is composed of four stepwise oxidations: three steps use O2 as the two-electron acceptor and the fourth uses hydrogen peroxide (H2O2). The chemical nature of the intermediates, the stoichiometry of the reaction and their dependence on the oxygen concentration indicate that the third oxidation uses the product H2O2 from the preceding step to produce water. The last oxidation step can also be studied separately and is a reaction between O2 and PQQH2 trapped in the active site. This oxidation is approximately 10 times slower than the reoxidation of PQQH2 in solution. From the order of the four oxidation steps and their sensitivity to O2 concentration, we propose a progressive closure of the active site as the enzyme proceeds through its catalytic cycle.
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编码细菌辅因子吡咯喹啉醌生物合成的基因的分布和特性。
影响因子：
2.9
作者：
Shen, Yao-Qing;Bonnot, Florence;Imsand, Erin M.;RoseFigura, Jordan M.;Sjoelander, Kimmen;Klinman, Judith P.
通讯作者：
Klinman, Judith P.
影响因子：
5.8
作者：
He, K;Nukada, H;Murphy, MP
通讯作者：
Murphy, MP
影响因子：
3.4
作者：
Colloc'h, Nathalie;Gabison, Laure;Prange, Thierry
通讯作者：
Prange, Thierry
DOI：
10.1039/p29900000315
发表时间：
1990-02-01
期刊：
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
影响因子：
--
作者：
MURE, M;NII, K;OHSHIRO, Y
通讯作者：
OHSHIRO, Y
影响因子：
2.9
作者：
Magnusson, Olafur Th.;RoseFigura, Jordan M.;Klinman, Judith P.
通讯作者：
Klinman, Judith P.