Generation of hydrogen peroxide, superoxide and hydroxyl radicals during the oxidation of dihydroxyfumaric acid by peroxidase.
Generation of hydrogen peroxide, superoxide and hydroxyl radicals during the oxidation of dihydroxyfumaric acid by peroxidase.
复制标题
过氧化物酶氧化二羟基富马酸过程中产生过氧化氢、超氧化物和羟基自由基。
DOI：
10.1042/bj1630441
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发表时间：
1977
期刊：
影响因子：
--
通讯作者：
B. Halliwell
中科院分区：
文献类型：
--
作者：
B. Halliwell
1. 富马酸二羟基在pH6时缓慢自氧化。超氧化物歧化酶能抑制该反应，而EDTA不能。Mn2+通过与O2反应生成Mn3+，催化富马酸二氢氧化，使富马酸二氢氧化迅速。Cu2+也催化富马酸二羟基氧化，但通过一种不涉及O2的机制导致。2. 过氧化物酶在pH6下催化富马酸二羟基的氧化；H2O2的加入不会提高反应速率。用超氧化物歧化酶和过氧化氢酶进行的实验表明，有两种类型的氧化发生：一种是过氧化物酶对富马酸二羟基的依赖于h2o2的酶性氧化，另一种是非酶性反应，涉及富马酸二羟基被O2氧化导致的氧化。后者是观察到的富马酸二羟基氧化的主要原因。3. 在二羟基富马酸氧化过程中，大多数过氧化物酶以化合物III的形式存在，酶的氧化可能由于该化合物的低分解率而受到限制。4. 对香豆酸加入到过氧化物酶/富马酸二羟基体系中，增加了富马酸二羟基氧化的速率，过氧化氢酶对过氧化氢酶的抑制更敏感，而超氧化物歧化酶对过氧化氢酶的抑制不太敏感。化合物III在对香豆酸存在下分解。对羟基苯甲酸酯对二羟基富马酸酯的氧化有类似的作用，但作用要小得多。然而，水杨酸既不影响氧化二羟基富马酸的速率，也不影响氧化机制。5. 对羟基苯甲酸酯、水杨酸酯和对香豆酸酯被过氧化物酶/二羟基富马酸酯体系羟基化。使用羟基自由基清除剂的实验表明，OH是必需的。增加富马酸二羟基氧化的能力并不是发生羟基化所必需的。
1. Dihydroxyfumarate slowly autoxidizes at pH6. This reaction is inhibited by superoxide dismutase but not by EDTA. Mn2+ catalyses dihydroxyfumarate oxidation by reacting with O2 leads to to form Mn3+, which seems to oxidize dihydrofumarate rapidly. Cu2+ also catalyses dihydroxyfumarate oxidation, but by a mechanism that does not involve O2 leads to. 2. Peroxidase catalyses oxidation of dihydroxyfumarate at pH6; addition of H2O2 does not increase the rate. Experiments with superoxide dismutase and catalase suggest that there are two types of oxidation taking place: an enzymic, H2O2-dependent oxidation of dihydroxyfumarate by peroxidase, and a non-enzymic reaction involving oxidation of dihydroxyfumarate by O2 leads to. The latter accounts for most of the observed oxidation of dihydroxyfumarate. 3. During dihydroxyfumarate oxidation, most peroxidase is present as compound III, and the enzymic oxidation may be limited by the low rate of breakdown of this compound. 4. Addition of p-coumaric acid to the peroxidase/dihydroxyfumarate system increases the rate of dihydroxyfumarate oxidation, which is now stimulated by addition of H2O2, and is more sensitive to inhibition by catalase but less sensitive to superoxide dismutase. Compound III is decomposed in the presence of p-coumaric acid. p-Hydroxybenzoate has similar, but much smaller, effects on dihydroxyfumarate oxidation. However, salicylate affects neither the rate nor the mechanism of dihydroxyfumarate oxidation. 5. p-Hydroxybenzoate, salicylate and p-coumarate are hydroxylated by the peroxidase/dihydroxyfumarate system. Experiments using scavengers of hydroxyl radicals shown that OH is required. Ability to increase dihydroxyfumarate oxidation is not necessary for hydroxylation to occur.