Mechanisms of oxidant generation by catalase.
Mechanisms of oxidant generation by catalase.
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DOI：
10.1111/j.1749-6632.2010.05603.x
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发表时间：
2010-08
影响因子：
5.2
通讯作者：
Vetrano AM
中科院分区：
文献类型：
--
作者：
Heck DE;Shakarjian M;Kim HD;Laskin JD;Vetrano AM
过氧化氢酶将太阳辐射转化为活性氧化物（ROS）。在这项研究中，我们报告说，几种细菌过氧化氢酶（氢过氧化物酶，HP），包括大肠杆菌HP-Ⅰ和HP-Ⅱ也产生反应性氧化剂在紫外线B光（UVB）。除了存在NADPH之外，HP-I和HP-II相同。我们发现，只有一个过氧化氢酶，HPI，产生氧化剂在UVB光响应，表明在ROS生产的核苷酸的潜在作用。这促使我们推测NADPH可能作为一种辅助因子调节哺乳动物过氧化氢酶产生的ROS。几种哺乳动物的过氧化氢酶的NADPH结构域的结构分析表明，核苷酸结合在一个约束的构象和UVB照射诱导NADPH氧化和位置的变化。生物化学和动力学分析表明，活性氧的形成由酶的辅因子的氧化增强。过氧化氢酶NADPH吸收UVB光后的构象变化有可能促进酶产生ROS。
The enzyme catalase converts solar radiation into reactive oxidant species (ROS). In this study, we report that several bacterial catalases (hydroperoxidases, HP), including Escherichia coli HP-I and HP-II also generate reactive oxidants in response to ultraviolet B light (UVB). HP-I and HP-II are identical except for the presence of NADPH. We found that only one of the catalases, HPI, produces oxidants in response to UVB light, indicating a potential role for the nucleotide in ROS production. This prompts us to speculate that NADPH may act as a cofactor regulating ROS generation by mammalian catalases. Structural analysis of the NADPH domains of several mammalian catalases revealed that the nucleotide is bound in a constrained conformation and that UVB irradiation induces NADPH oxidation and positional changes. Biochemical and kinetic analysis indicate that ROS formation by the enzyme is enhanced by oxidation of the cofactor. Conformational changes following absorption of UVB light by catalase NADPH have the potential to facilitate ROS production by the enzyme.