Zapata J M, Caldéron A A, Muñoz R, Ros Barceló A
Department of Plant Biology (Plant Physiology), University of Murcia, Spain.
Biochimie. 1992 Feb;74(2):143-8. doi: 10.1016/0300-9084(92)90038-g.
The oxidation of hydroquinone by two peroxidase (EC 1.11.1.7) fractions obtained from the cells and spent medium of cell cultures of grapevine (Vitis vinifera cv Monastrell) has been studied, and their comparative efficacy (kcat/KM ratio) studied in both the H2O2-consuming and hydroquinone-consuming reactions. While the efficacy in the H2O2-consuming reaction is practically identical for both enzyme fractions, the cellular peroxidase has five-fold more efficacy in the hydroquinone-consuming reaction than the peroxidase located in the spent medium. Screening of cellular peroxidases capable of oxidizing hydroquinone on polyacrylamide gels, by means of a staining reaction based on the nucleophilic attack of 4-aminoantipyrine on p-benzoquinone in acidic media, reveals that all the cellular peroxidase isoenzymes are capable of oxidizing hydroquinone, probably yielding a quinone-diimine as a product of the staining reaction. Since isoperoxidases found in cellular fractions are also present in the spent medium, the values found for the different efficacies in the hydroquinone-consuming reaction must be considered as the results of the different proportions in which each peroxidase isoenzyme was found in the two fractions. The localization of a benzoquinone-generating system of high efficacy inside the plant cell, and probably located in vacuoles, is discussed with respect to the harmful role which the quinone/semiquinone pair might play in cell death, as part of the hypersensitive response expressed within the mechanism of plant disease resistance.
对从葡萄（Vitis vinifera cv Monastrell）细胞培养物的细胞和用过的培养基中获得的两种过氧化物酶（EC 1.11.1.7）组分氧化对苯二酚的情况进行了研究，并在消耗H2O2和消耗对苯二酚的反应中研究了它们的比较效能（kcat/KM比值）。虽然两种酶组分在消耗H2O2的反应中的效能几乎相同，但细胞过氧化物酶在消耗对苯二酚的反应中的效能比用过的培养基中的过氧化物酶高五倍。通过基于4-氨基安替比林在酸性介质中对对苯醌的亲核攻击的染色反应，在聚丙烯酰胺凝胶上筛选能够氧化对苯二酚的细胞过氧化物酶，结果表明所有细胞过氧化物酶同工酶都能够氧化对苯二酚，染色反应的产物可能是醌二亚胺。由于在细胞组分中发现的同功过氧化物酶也存在于用过的培养基中，因此在消耗对苯二酚的反应中发现的不同效能值必须被视为每种过氧化物酶同工酶在两个组分中所占不同比例的结果。就醌/半醌对在细胞死亡中可能发挥的有害作用而言，讨论了植物细胞内高效苯醌生成系统的定位，该系统可能位于液泡中，这是植物抗病机制中表达的过敏反应的一部分。
