水稻（Oryza sativa）重组血红蛋白 1 的过氧化物酶活性分析：对植物中六配位非共生血红蛋白体内功能的启示。
Analysis of peroxidase activity of rice (Oryza sativa) recombinant hemoglobin 1: implications for in vivo function of hexacoordinate non-symbiotic hemoglobins in plants.
机构信息
Laboratorio de Biofísica y Biología Molecular, Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62210 Cuernavaca, Morelos, México.
出版信息
Phytochemistry. 2010 Jan;71(1):21-6. doi: 10.1016/j.phytochem.2009.09.016. Epub 2009 Oct 14.
In plants, it has been proposed that hexacoordinate (class 1) non-symbiotic Hbs (nsHb-1) function in vivo as peroxidases. However, little is known about peroxidase activity of nsHb-1. We evaluated the peroxidase activity of rice recombinant Hb1 (a nsHb-1) by using the guaiacol/H2O2 system at pH 6.0 and compared it to that from horseradish peroxidase (HRP). Results showed that the affinity of rice Hb1 for H2O2 was 86-times lower than that of HRP (K(m)=23.3 and 0.27 mM, respectively) and that the catalytic efficiency of rice Hb1 for the oxidation of guaiacol using H2O2 as electron donor was 2838-times lower than that of HRP (k(cat)/K(m)=15.8 and 44,833 mM(-1) min(-1), respectively). Also, results from this work showed that rice Hb1 is not chemically modified and binds CO after incubation with high H2O2 concentration, and that it poorly protects recombinant Escherichia coli from H2O2 stress. These observations indicate that rice Hb1 inefficiently scavenges H2O2 as compared to a typical plant peroxidase, thus indicating that non-symbiotic Hbs are unlikely to function as peroxidases in planta.
在植物中，有人提出六配位（第 1 类）非共生 Hbs（nsHb-1）在体内作为过氧化物酶发挥作用。然而，对于 nsHb-1 的过氧化物酶活性知之甚少。我们通过使用愈创木酚/H2O2 系统在 pH 6.0 下评估了水稻重组 Hb1（nsHb-1）的过氧化物酶活性，并将其与辣根过氧化物酶（HRP）的过氧化物酶活性进行了比较。结果表明，水稻 Hb1 对 H2O2 的亲和力比 HRP 低 86 倍（K(m)=23.3 和 0.27 mM，分别），并且水稻 Hb1 用 H2O2 作为电子供体氧化愈创木酚的催化效率比 HRP 低 2838 倍（k(cat)/K(m)=15.8 和 44,833 mM(-1) min(-1)，分别）。此外，这项工作的结果表明，水稻 Hb1 在与高浓度 H2O2 孵育后不会发生化学修饰，也不会结合 CO，并且它不能有效地保护重组大肠杆菌免受 H2O2 胁迫。这些观察结果表明，与典型的植物过氧化物酶相比，水稻 Hb1 清除 H2O2 的效率较低，因此表明非共生 Hbs 不太可能在植物体内作为过氧化物酶发挥作用。
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