甜菜血红蛋白：与一氧化氮和亚硝酸盐的反应揭示了氮代谢的不同作用。,Biochemical Journal

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甜菜血红蛋白：与一氧化氮和亚硝酸盐的反应揭示了氮代谢的不同作用。
Biochemical Journal ( IF 4.4 ) Pub Date : 2019-07-10 , DOI: 10.1042/bcj20190154
Nélida Leiva Eriksson ₁ , Brandon J Reeder ₂ , Michael T Wilson ₂ , Leif Bülow ₃

Affiliation

与红细胞中的人血红蛋白（Hb）相比，植物Hbs不运输氧气，相反，研究指向氮代谢。使用全面和综合的生物物理方法，我们表征了三种甜菜Hb：BvHb1.1，BvHb1.2和BvHb2。确定了它们对氧，一氧化碳和六配位的亲和力。通过评估它们与NO结合，还原亚硝酸盐（NiR，亚硝酸还原酶）和形成硝酸盐（NOD，NO双加氧酶）的能力，研究了它们在氮代谢中的作用。结果表明，BvHb1.2具有高NOD样活性，这与表达该蛋白的种子中的高硝酸盐含量相符。另一方面，BvHb1.1具有与NO结合并形成硝酸盐的能力，其主要作用是保护叶绿体免受NO的有害影响。最后，无处不在的反应能够采用“开放和封闭形式”的多功能BvHb2将成为新陈代谢途径的一部分，而氧和NO之间的平衡至关重要。对于所有蛋白质，只有当高浓度的亚硝酸盐存在且没有NO和氧时，NiR活性才有意义。这三种蛋白质具有与NO，氧和亚硝酸盐反应的独特内在能力。然而，正是它们的浓度决定了BvHb的活性。

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Sugar beet hemoglobins: reactions with nitric oxide and nitrite reveal differential roles for nitrogen metabolism.

In contrast with human hemoglobin (Hb) in red blood cells, plant Hbs do not transport oxygen, instead research points towards nitrogen metabolism. Using comprehensive and integrated biophysical methods we characterized three sugar beet Hbs: BvHb1.1, BvHb1.2 and BvHb2. Their affinities for oxygen, CO, and hexacoordination were determined. Their role in nitrogen metabolism was studied by assessing their ability to bind NO, to reduce nitrite (NiR, nitrite reductase), and to form nitrate (NOD, NO dioxygenase). Results show that BvHb1.2 has high NOD-like activity, in agreement with the high nitrate levels found in seeds where this protein is expressed. BvHb1.1, on the other side, is equally capable to bind NO as to form nitrate, its main role would be to protect chloroplasts from the deleterious effects of NO. Finally, the ubiquitous, reactive, and versatile BvHb2, able to adopt 'open and closed forms', would be part of metabolic pathways where the balance between oxygen and NO is essential. For all proteins, the NiR activity is relevant only when nitrite is present at high concentrations and both NO and oxygen are absent. The three proteins have distinct intrinsic capabilities to react with NO, oxygen and nitrite; however, it is their concentration which will determine the BvHbs' activity.

更新日期：2019-11-01

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