OXIDATION OF NEUROSPORA-CRASSA NADP-SPECIFIC GLUTAMATE-DEHYDROGENASE BY ACTIVATED OXYGEN SPECIES
OXIDATION OF NEUROSPORA-CRASSA NADP-SPECIFIC GLUTAMATE-DEHYDROGENASE BY ACTIVATED OXYGEN SPECIES
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DOI：
10.1128/jb.171.11.6243-6250.1989
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发表时间：
1989-11-01
影响因子：
3.2
通讯作者：
HANSBERG, W
中科院分区：
文献类型：
--
作者：
AGUIRRE, J;RODRIGUEZ, R;HANSBERG, W
在无碳源培养条件下，只有在空气存在下，粗糙脉孢菌的谷氨酰胺合成酶和NADP特异性谷氨酸脱氢酶活性才丧失。谷氨酰胺合成酶在体外和体内均易被活性氧灭活。在这里，我们报告说，NADP特异性谷氨酸脱氢酶是非常稳定的存在下，活性氧物种，但容易氧化失活时，螯合铁结合到酶和抗坏血酸或H2O2反应的结合铁。该反应引起通过活性氧物质对酶单体的进一步修饰，引起寡聚体结构的部分解离，以及引起酶的沉淀和片段化。体外氧化反应受pH值、温度和与NADPH酶结合的影响。在纯化的和免疫沉淀的酶中观察到总电荷中的异质结，并且具有不同等电点的酶单体的相对量随着氧化反应的时间而变化。
The glutamine synthetase and the NADP-specific glutamate dehydrogenase activities of Neurospora crassa were lost in a culture without carbon source only when in the presence of air. Glutamine synthetase was previously reported to be liable to in vitro and in vivo inactivation by activated oxygen species. Here we report that NADP-specific glutamate dehydrogenase was remarkably stable in the presence of activated oxygen species but was rendered susceptible to oxidative inactivation when chelated iron was bound to the enzyme and either ascorbate or H2O2 reacted on the bound iron. This reaction gave rise to further modifications of the enzyme monomers by activated oxygen species, to partial dissociation of the oligomeric structure, and to precipitation and fragmentation of the enzyme. The in vitro oxidation reaction was affected by pH, temperature, and binding to the enzyme of NADPH. Heterogeneity in total charge was observed in the purified and immunoprecipitated enzymes, and the relative amounts of enzyme monomers with different isoelectric points changed with time of the oxidizing reaction.