Two sources of endogenous hydrogen peroxide in Escherichia coli.
Two sources of endogenous hydrogen peroxide in Escherichia coli.
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DOI：
10.1111/j.1365-2958.2010.07059.x
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发表时间：
2010-03
影响因子：
3.6
通讯作者：
Imlay JA
中科院分区：
文献类型：
--
作者：
Korshunov S;Imlay JA
利用缺乏清除酶的菌株研究了大肠杆菌中过氧化氢的产生机制。令人惊讶的是，已知在体外自动氧化的许多丰富的黄素酶的缺失并没有实质上减少整体H2 O2的形成。然而，当NadB的周转被消除时，H2 O2的产量减少了25-30%。黄素依赖性去饱和脱氢酶NadB在厌氧细胞中使用富马酸作为电子受体。实验表明，好氧NadB周转取决于其氧化的分子氧，H2 O2作为产品。该反应似乎是机械偶然的。相比之下，大多数去饱和脱氢酶与呼吸链相关，并在厌氧条件下将电子传递给富马酸盐或在有氧条件下将氧气传递给富马酸盐，而不会形成有毒副产物。据推测，NadB可以持续作为H2 O2产生酶，因为它的流量是有限的。厌氧呼吸酶延胡索酸还原酶使用与NadB同源的黄素蛋白亚基，因此在通气时形成大量H2 O2。这种趋势基本上被细胞色素氧化酶抑制。因此，细胞色素d氧化酶，这是普遍的厌氧菌，可以减少细胞内的H2 O2形成的厌氧呼吸链，每当这些生物体遇到氧气。这两个例子揭示了生物化学和生理学的安排，通过进化使细胞内氧化剂形成的速率最小化。
Mechanisms of hydrogen peroxide generation in Escherichia coli were investigated using a strain lacking scavenging enzymes. Surprisingly, the deletion of many abundant flavoenzymes that are known to auto-oxidize in vitro did not substantially lessen overall H2O2 formation. However, H2O2 production diminished by 25-30% when NadB turnover was eliminated. The flavin-dependent desaturating dehydrogenase, NadB uses fumarate as an electron acceptor in anaerobic cells. Experiments showed that aerobic NadB turnover depends upon its oxidation by molecular oxygen, with H2O2 as a product. This reaction appears to be mechanistically adventitious. In contrast, most desaturating dehydrogenases are associated with the respiratory chain and deliver electrons to fumarate anaerobically or oxygen aerobically without the formation of toxic byproducts. Presumably, NadB can persist as an H2O2-generating enzyme because its flux is limited. The anaerobic respiratory enzyme fumarate reductase uses a flavoprotein subunit that is homologous to NadB and accordingly forms substantial H2O2 upon aeration. This tendency is substantially suppressed by cytochrome oxidase. Thus cytochrome d oxidase, which is prevalent among anaerobes, may diminish intracellular H2O2 formation by the anaerobic respiratory chain, whenever these organisms encounter oxygen. These two examples reveal biochemical and physiological arrangements through which evolution has minimized the rate of intracellular oxidant formation.
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影响因子：
3.2
作者：
Seaver, LC;Imlay, JA
通讯作者：
Imlay, JA
影响因子：
5.7
作者：
Mattevi, A;Tedeschi, G;Ronchi, S
通讯作者：
Ronchi, S
DOI：
10.1073/pnas.0510977103
发表时间：
2006-05-16
影响因子：
11.1
作者：
Kussmaul, Lothar;Hirst, Judy
通讯作者：
Hirst, Judy
DOI：
10.1073/pnas.120163297
发表时间：
2000-06-06
影响因子：
11.1
作者：
Datsenko, KA;Wanner, BL
通讯作者：
Wanner, BL
影响因子：
3.6
作者：
Pan, N;Imlay, JA
通讯作者：
Imlay, JA