SOD and catalase inactivation by singlet oxygen and peroxyl radicals
SOD and catalase inactivation by singlet oxygen and peroxyl radicals
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DOI：
10.1016/0891-5849(95)02037-3
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发表时间：
1996-01-01
影响因子：
7.4
通讯作者：
Lissi, EA
中科院分区：
文献类型：
--
作者：
Escobar, JA;Rubio, MA;Lissi, EA
超氧化物歧化酶和过氧化氢酶都很容易被单线态氧和在有氧条件下2,2'-偶氮-双-（2-氨基丙烷）热解过程中产生的自由基失活。单线态氧诱导SOD和过氧化氢酶活性丧失的速率常数分别为3.9 X 10(7)和2.5 X 10(7) M(-1) sec（-1）。这些值之间的相似性表明，在系统中，SOD和过氧化氢酶暴露于相似的单线态氧浓度，可以预期这两种酶的平行失活。在有氧条件下，2,2'-偶氮-双-（2-氨基丙烷）热解产生的自由基对这两种酶的失活遵循低酶浓度下的一级动力学和高酶浓度下的零级动力学。虽然在低酶浓度下，两种酶的失活率相似，但这是由于两种酶对过氧烷基自由基的反应性存在很大差异，因此是一种补偿效应。过氧化氢酶的反应性要高得多，但要使一种酶失活，需要大量的蛋白质/自由基反应相互作用。另一方面，SOD的反应活性较小，但在每次SOD/自由基反应相互作用中，酶的平均活性下降了近20%。
Both superoxide dismutase and catalase are readily deactivated by singlet oxygen and by the radicals produced in the pyrolysis of 2,2'-azo-bis-(2-amidinpropano) under aerobic conditions. The rate constant for the loss of enzymatic activity induced by singlet oxygen are 3.9 X 10(7) and 2.5 X 10(7) M(-1) sec(-1) for SOD and catalase, respectively. The similarity between these values implies that in systems where SOD and catalase are exposed to similar singlet oxygen concentrations, it can be expected a parallel inactivation of both enzymes. The inactivation of both enzymes by the radicals produced by 2,2'-azo-bis-(2-amidinopropane) pyrolysis under aerobic conditions follows a first-order kinetics at low enzyme concentrations and a zero-order kinetics at higher concentrations. Although at low enzymatic concentrations the rate of inactivation of both enzymes is similar, this results from a compensation of effects because there are wide differences in the reactivity of both enzymes towards peroxyalkyl radicals. Catalase is considerably more reactive, but a large number of protein/radical reactive interactions are needed to inactivate one enzyme. On the other hand, the reactivity of SOD is smaller, but the average enzyme activity decreases by nearly 20% in each SOD/radical reactive interaction.