Nitrite reductase activity of nonsymbiotic hemoglobins from Arabidopsis thaliana.
Nitrite reductase activity of nonsymbiotic hemoglobins from Arabidopsis thaliana.
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DOI：
10.1021/bi300570v
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发表时间：
2012-07-03
期刊：
影响因子：
2.9
通讯作者：
Gladwin MT
中科院分区：
文献类型：
--
作者：
Tiso M;Tejero J;Kenney C;Frizzell S;Gladwin MT
植物非共生血红蛋白具有类似于血红素蛋白质脑红蛋白的六配位血红素几何结构。我们最近发现，脱氧的脑红蛋白将亚硝酸盐转化为一氧化氮（NO），一种参与植物许多过程的重要信号分子。我们试图确定是否拟南芥非共生血红蛋白类1和2（AHb 1和AHb 2）可能作为亚硝酸盐还原酶的功能。我们发现，亚硝酸盐与脱氧AHb 1和AHb 2的反应产生NO气体和铁-亚硝基-血红蛋白物种。在pH = 7.4和25°C时，亚硝酸盐还原为NO的双分子速率常数分别为19.8 ± 3.2和4.9 ± 0.2 M− 1 s −1。我们确定了这些双分子速率常数的pH依赖性，并发现与质子浓度的线性相关性，表明反应中需要一个质子。通过化学发光检测证实了在缺氧和低氧（2%氧）条件下反应期间游离NO气体的释放。这些结果表明，脱氧AHb 1和AHb 2通过与血红蛋白、肌红蛋白和神经红蛋白类似的机制还原亚硝酸盐形成NO。我们的研究结果表明，在严重缺氧和厌氧植物的根，特别是在水中淹没的物种，非共生血红蛋白提供了一个可行的途径，通过亚硝酸盐还原NO的产生。
Plant non-symbiotic hemoglobins possess hexa-coordinate heme geometry similar to the heme protein neuroglobin. We recently discovered that deoxygenated neuroglobin converts nitrite to nitric oxide (NO), an important signaling molecule involved in many processes in plants. We sought to determine whether Arabidopsis thaliana non-symbiotic hemoglobins class 1 and 2 (AHb1 and AHb2) might function as nitrite reductases. We found that the reaction of nitrite with deoxygenated AHb1 and AHb2 generates NO gas and iron-nitrosyl-hemoglobin species. The bimolecular rate constants for nitrite reduction to NO are 19.8 ± 3.2 and 4.9 ± 0.2 M−1s−1, at pH = 7.4 and 25°C, respectively. We determined the pH dependence of these bimolecular rate constants and found a linear correlation with the concentration of protons, indicating the requirement for one proton in the reaction. Release of free NO gas during reaction in anoxic and hypoxic (2% oxygen) conditions was confirmed by chemiluminescence detection. These results demonstrate that deoxygenated AHb1 and AHb2 reduce nitrite to form NO via a mechanism analogous to that observed for hemoglobin, myoglobin and neuroglobin. Our findings suggest that during severe hypoxia and in the anaerobic plant roots, especially in water submerged species, non-symbiotic hemoglobins provide a viable pathway for NO generation via nitrite reduction.
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影响因子：
64.8
作者：
Delledonne, M;Xia, YJ;Lamb, C
通讯作者：
Lamb, C
DOI：
10.1073/pnas.0308657101
发表时间：
2004-04-27
影响因子：
11.1
作者：
Freitas, TAK;Hou, SB;Alam, M
通讯作者：
Alam, M
影响因子：
4.8
作者：
Huang, KT;Keszler, A;Hogg, N
通讯作者：
Hogg, N
影响因子：
4.3
作者：
Morard, P;Silvestre, J;Lamaze, T
通讯作者：
Lamaze, T
影响因子：
5
作者：
Machha A;Schechter AN
通讯作者：
Schechter AN