MECHANISM-BASED INACTIVATION OF HORSERADISH-PEROXIDASE BY SODIUM-AZIDE - FORMATION OF MESO-AZIDOPROTOPORPHYRIN-IX
MECHANISM-BASED INACTIVATION OF HORSERADISH-PEROXIDASE BY SODIUM-AZIDE - FORMATION OF MESO-AZIDOPROTOPORPHYRIN-IX
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DOI：
10.1021/bi00415a013
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发表时间：
1988-07-26
期刊：
影响因子：
2.9
通讯作者：
TEW, D
中科院分区：
文献类型：
--
作者：
DEMONTELLANO, PRO;DAVID, SK;TEW, D
摘要：辣根过氧化物酶催化叠氮化钠的周转，产生叠氮基自由基，导致酶失活，其中β = 1.47 mM，β inact= 0.69 min-1。使80%的酶失活需要约60当量的NaN 3和H2 O2。较高浓度的这两种试剂使酶完全失活，当分离和表征部分失活的酶的辅基时，获得内消旋-叠氮血红素以及一些残留的血红素。辣根过氧化物酶与mero-azidoheme的重组产生一种没有可检测到的催化活性的酶，即使与血红素本身的重组产生完全活性的酶。催化产生的氮自由基添加到血红素的中位碳的发现表明，生物中位添加并不限于碳自由基。氧自由基的类似添加可触发血红素的正常和/或病理性降解。
Revised Manuscript Received March 11, 1988 abstract: Catalytic turnover of sodium azide by horseradish peroxidase, which produces the azidyl radical, results in inactivation of theenzyme with= 1.47 mM and &inact= 0.69 min-1. Inactivation of 80% of the enzyme requires approximately 60 equiv each of NaN3 and H202. The enzyme is completely inactivated by higher concentrations of these two agents, meso-Azidoheme as well as some residual heme are obtained when the prosthetic group of the partially inactivated enzyme is isolated and characterized. Reconstitution of horseradish peroxidase with mero-azidoheme yields an enzyme without detectable catalyticactivity even though reconstitution with heme itself gives fully active enzyme. The finding that catalytically generated nitrogen radicals add to the meso carbon of heme shows that biological meso additions are not restricted to carbon radicals. The analogous addition of oxygen radicals may trigger the normal and/or pathological degradation of heme.