Inactivation of lignin peroxidase by phenylhydrazine and sodium azide.
Inactivation of lignin peroxidase by phenylhydrazine and sodium azide.
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苯肼和叠氮化钠灭活木质素过氧化物酶。
DOI：
10.1016/0003-9861(90)90539-b
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发表时间：
1990
影响因子：
3.9
通讯作者：
OrtizdeMontellano,PR
中科院分区：
文献类型：
--
作者：
DePillis,GD;Wariishi,H;Gold,MH;OrtizdeMontellano,PR
木质素过氧化物酶（LiP）可被过氧化氢、苯肼或叠氮化钠以浓度依赖性方式迅速灭活。同工酶2b（H8）的完全失活需要约50当量的苯肼或80当量的叠氮化钠。同工酶2b与[14 C]苯肼和H_2O_2的厌氧孵育导致77%的催化活性损失和0.45 mol放射性标记/mol酶的共价结合。同工酶混合物获得了可比较但不相同的结果。当将与叠氮化钠一起孵育的等分试样稀释到用于测定残留催化活性的混合物中时，在可以测量过氧化活性之前观察到滞后期。这种滞后与具有化合物III样光谱的催化惰性物质的可逆积累有关。与苯肼形成nomeso-苯基、铁-苯基或N-苯基加合物，但用叠氮化钠得到的δ-meso-叠氮血红素产率较低。因此，LiP对中间血红素添加物不太敏感，并且比辣根过氧化物酶对氧化血红素降解更敏感。这些数据表明，活性位点的LiP类似于封闭结构的辣根过氧化物酶比它的开放结构的球蛋白，过氧化氢酶，氯过氧化物酶，或细胞色素P450。
Lignin peroxidase (LiP) is rapidly inactivated in a concentration-dependent manner by H2O2and either phenylhydrazine or sodium azide. Full inactivation of isozyme 2b (H8) requires approximately 50 eq of phenylhydrazine or 80 eq of sodium azide. Anaerobic incubation of isozyme 2b with [14C]phenylhydrazine and H2O2results in 77% loss of catalytic activity and covalent binding of 0.45 mol radiolabel/mol of enzyme. Comparable but not identical results are obtained with an isozyme mixture. A lag period is observed before the peroxidative activity can be measured when an aliquot of an incubation with sodium azide is diluted into the mixture used to assay residual catalytic activity. This lag is associated with reversible accumulation of a catalytically inert species with a Compound III-like spectrum. Nomeso-phenyl, iron-phenyl, orN-phenyl adducts are formed with phenylhydrazine but a low yield of what appears to be δ-meso-azidoheme is obtained with sodium azide. LiP is thus less susceptible tomesoheme additions and more susceptible to oxidative heme degradation than horseradish peroxidase. The data suggest that the active site of LiP resembles the closed structure of horseradish peroxidase more than it does the open structure of the globins, catalase, chloroperoxidase, or cytochrome P450.