...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >CHARACTERIZATION OF THE INTERACTION BETWEEN PQQ AND HEME C IN THE QUINOHEMOPROTEIN ETHANOL DEHYDROGENASE FROM COMAMONAS TESTOSTERONI
【24h】

CHARACTERIZATION OF THE INTERACTION BETWEEN PQQ AND HEME C IN THE QUINOHEMOPROTEIN ETHANOL DEHYDROGENASE FROM COMAMONAS TESTOSTERONI

机译：沙门氏菌奎奴亚血红蛋白醇乙醇脱氢酶中PQQ与血红素C相互作用的表征

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Quinohemoprotein ethanol dehydrogenase from Comamonas testosteroni (QH-EDH) contains two cofactors, 2,7,9-tricarboxy-1H-pyrrolo[2,3-f]quinoline-4,5-dione (PQQ) and heme c. Since previous studies on the kinetics of this enzyme suggested that both participate in electron transfer, spectroscopic investigations were performed of the oxidized and reduced holo- and apoenzyme (without PQQ but with heme c) to reveal the nature of the interaction between the two redox centers. From this it appears that the properties of the heme in the enzyme are affected by the presence of PQQ, as judged from the shift of the maxima in the ultraviolet/visible absorption spectra of the heme moiety in both reduced and oxidized QH-EDH and the 60-mV increase of the heme midpoint redox potential caused by pQQ addition. Also H-1-NMR spectroscopy was indicative for interaction since binding of PQQ induced shifts in the resonances of the methyl groups of the porphyrin ring in the oxidized form of the apoenzyme and a shift in the methionine heme ligand resonance of the reduced form of the apoenzyme, On the other hand, resonance Raman spectra of the heme in the different enzyme forms were nearly similar, These results suggest that a major effect of PQQ binding to apo-QH-EDH is a rotation of the methionine ligand of heme c. Since no intermediate H-1-NMR spectra were observed upon titration of apoenzyme with PQQ, apparently no exchange occurs of PQQ between (oxidized) holo- and apoenzyme at the NMR time scale and at that of the experiment. This is in agreement with the view that PQQ becomes tightly bound, the event leading to a compact enzyme conformation which is able to catalyze rapid intramolecular electron transfer. [References: 23]
机译：睾丸单胞菌（QH-EDH）的奎诺蛋白蛋白乙醇脱氢酶包含两个辅因子，即2,7,9-三羧基-1H-吡咯并[2,3-f]喹啉-4,5-二酮（PQQ）和血红素c。由于先前对该酶动力学的研究表明两者都参与电子转移，因此对氧化和还原的全酶和脱辅酶（无PQQ但有血红素c）进行了光谱研究，以揭示两个氧化还原中心之间相互作用的性质。由此看来，酶的血红素特性受PQQ的存在影响，这是根据还原和氧化的QH-EDH和血红素部分中血红素部分的紫外/可见吸收光谱中最大值的变化判断的。 pQQ添加导致血红素中点氧化还原电位增加60 mV。 H-1-NMR光谱也表明相互作用，因为PQQ的结合引起了脱辅酶氧化形式的卟啉环甲基共振中的移位和还原形式的甲硫氨酸血红素配体共振中的移位。另一方面，不同酶形式的血红素的共振拉曼光谱几乎相似。这些结果表明，PQQ与apo-QH-EDH结合的主要作用是血红素c的蛋氨酸配体的旋转。由于用PQQ滴定脱辅酶后没有观察到中间的H-1-NMR光谱，因此在NMR时标和实验时，在（氧化的）全酶和脱辅酶之间显然没有发生PQQ交换。这与PQQ紧密结合的观点一致，该事件导致紧密的酶构象，该构象能够催化分子内电子的快速转移。 [参考：23]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号