4-Nitro-o-phenylenediamine (NOP) is a powerful direct-acting mutagen which demonstrates significant enhancement in mutagenicity when exposed to plant enzymatic systems. Evidence implicating the involvement of peroxidactic oxidation in NOP activation has been obtained from plant-cell suspension and isolated enzyme experiments. Using selected cytochrome P450 and peroxidase enzyme inhibitors in conjunction with Salmonella typhimurium strain TA98 and intact plant-cell activating systems as well as isolated horseradish peroxidase enzyme we have further investigated NOP activation by plant systems. The activation of NOP by both plant cells and by horseradish peroxidase was suppressed by the P450 inhibitors methimazole and (+)-catechin and by the peroxidase inhibitors diethyldithiocarbamate and potassium cyanide, but was not suppressed by the P450 inhibitors metyrapone and 7,8-benzoflavone. In addition, peroxidase enzymatic activity was measured and found to be inhibited by methimazole, diethyldithiocarbamate and potassium cyanide but not by (+)-catechin. The data strongly support the involvement of exogenous peroxidase in the plant activation of NOP, but point to a complex metabolic system that requires multistep processing before full mutagenic potential of the plant-activated component of NOP is expressed.

中文翻译：

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植物系统对4-硝基-邻-苯二胺活化的表征。

4-硝基邻苯二胺（NOP）是一种功能强大的直接作用诱变剂，当暴露于植物酶系统中时，其诱变性得到显着提高。从植物细胞悬浮液和分离的酶实验中获得了暗示过氧化物氧化参与NOP活化的证据。使用选定的细胞色素P450和过氧化物酶抑制剂与鼠伤寒沙门氏菌菌株TA98，完整的植物细胞活化系统以及分离的辣根过氧化物酶一起，我们进一步研究了植物系统对NOP的活化作用。P450抑制剂美他唑和（+）-儿茶素以及过氧化物酶抑制剂二乙基二硫代氨基甲酸酯和氰化钾可抑制植物细胞和辣根过氧化物酶对NOP的激活，但不受P450抑制剂甲吡酮和7,8-苯并黄酮的抑制。另外，测量过氧化物酶的酶活性，发现其被甲巯咪唑，二乙基二硫代氨基甲酸酯和氰化钾抑制，但未被（+）-儿茶素抑制。数据强烈支持外源过氧化物酶参与NOP的植物活化，但指向复杂的代谢系统，在表达NOP的植物活化成分的完全诱变潜力之前，需要进行多步处理。