Pomar Federico, Caballero Nuria, Pedreño María, Ros Barceló A
Department of Plant Biology (Plant Physiology), University of Murcia, E-30100 Murcia, Spain.
FEBS Lett. 2002 Oct 9;529(2-3):198-202. doi: 10.1016/s0014-5793(02)03339-2.
Characterization of lignified Zinnia elegans hypocotyls by both alkaline nitrobenzene oxidation and thioacidolysis reveals that coniferyl alcohol units are mainly found as part of 4-O-linked end groups and aryl-glycerol-beta-aryl ether (beta-O-4) structures. Z. elegans hypocotyls also contain a basic peroxidase (EC 1.11.1.7) capable of oxidizing coniferyl alcohol in the absence of H(2)O(2). Results showed that the oxidase activity of the Z. elegans basic peroxidase is stimulated by superoxide dismutase, and inhibited by catalase and anaerobic conditions. Results also showed that the oxidase activity of this peroxidase is due to an evolutionarily gained optimal adaptation of the enzyme to the microM H(2)O(2) concentrations generated during the auto-oxidation of coniferyl alcohol, the stoichiometry of the chemical reaction (mol coniferyl alcohol auto-oxidized/mol H(2)O(2) formed) being 0.496. These results therefore suggest that the H(2)O(2) generated during the auto-oxidation of coniferyl alcohol is the main factor that drives the unusual oxidase activity of this highly conserved lignin-synthesizing class III peroxidase.
通过碱性硝基苯氧化和硫代酸解对百日草木质化下胚轴进行表征，结果表明松柏醇单元主要作为4-O-连接端基和芳基甘油-β-芳基醚（β-O-4）结构的一部分被发现。百日草下胚轴还含有一种碱性过氧化物酶（EC 1.11.1.7），该酶在没有H₂O₂的情况下能够氧化松柏醇。结果表明，百日草碱性过氧化物酶的氧化酶活性受到超氧化物歧化酶的刺激，并受到过氧化氢酶和厌氧条件的抑制。结果还表明，这种过氧化物酶的氧化酶活性归因于该酶在进化过程中对松柏醇自氧化过程中产生的微摩尔浓度H₂O₂的最佳适应性，化学反应的化学计量比（自氧化的松柏醇摩尔数/形成的H₂O₂摩尔数）为0.496。因此，这些结果表明，松柏醇自氧化过程中产生的H₂O₂是驱动这种高度保守的木质素合成III类过氧化物酶异常氧化酶活性的主要因素。
