Hydrogen peroxide production by roots and its stimulation by exogenous NADH
Hydrogen peroxide production by roots and its stimulation by exogenous NADH
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DOI：
10.1034/j.1399-3054.1998.1030313.x
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发表时间：
1998-07-01
影响因子：
6.4
通讯作者：
Schopfer, P
中科院分区：
文献类型：
--
作者：
Frahry, G;Schopfer, P
使用 pH 5.0 下的非破坏性体内测定法监测幼苗根部 H2O2 的产生情况。在大豆 (Glycine max L. cv. Labrador) 幼苗的根部测量到特别高的 H2O2 生成率，该幼苗用于进一步研究质外体 H2O2 生成的生理和酶学特性。外源 NADH 或 NADPH 可以将大豆根部 H2O2 的产生刺激 10 倍。该反应显示了过氧化物酶催化的氧化酶反应的典型特征，该反应使用 NAD(P)H 作为电子供体将 O-2 还原为 H2O2。比较测量表明，在 NADH 和 O-2 浓度要求以及对 KCN、NaN3、超氧化物歧化酶和过氧化氢酶抑制的敏感性方面，NADH 诱导的根产生 H2O2 类似于辣根过氧化物酶的 H2O2 形成活性。在根的所有区域都可以观察到 NADH 诱导的 H2O2 产生，其强度相似，这与质外体过氧化物酶活性的分布一致。相比之下，在没有外源 NADH 的情况下，负责基础 H2O2 产生的活性主要局限于根的短根尖区，并且与 NADH 诱导的反应不同，因为它对超氧化物歧化酶的抑制不敏感，并且对 O-2 的需求显着降低。结论是根的基础 H2O2 产生是由一种不同于过氧化物酶的酶介导的，可能是质膜产生 O-2(-) 的氧化酶。
H2O2 production by roots of young seedlings was monitored using a non-destructive in vivo assay at pH 5.0. A particularly high rate of H2O2 production was measured in the roots of soybean (Glycine max L. cv. Labrador) seedlings which were used for further investigation of the physiological and enzymological properties of apoplastic H2O2 production. In the soybean root H2O2 production can be stimulated 10-fold by exogenous NADH or NADPH. This response displays typical features of a peroxidase-catalyzed oxidase reaction using NAD(P)H as electron donor for the reduction of O-2 to H2O2. Comparative measurements showed that the NADH-induced H2O2 production of the roots resembles the H2O2-forming activity of horseradish peroxidase with respect to NADH and O-2 concentration requirements and sensitivity to inhibition by KCN, NaN3, superoxide dismutase and catalase. NADH-induced H2O2 production can be observed with similar intensity in all regions of the root, in agreement with the distribution of apoplastic peroxidase activity. In contrast, the activity responsible for the basal H2O2 production in the absence of exogenous NADH was mainly confined to a short subapical zone of the root and differs from the NADH-induced reaction by insensitivity to inhibition by superoxide dismutase and a strikingly lower requirement for O-2. It is concluded that the basal H2O2 production of the root is mediated by an enzyme different from peroxidase, possibly a plasma membrane O-2(-)-producing oxidase.