Karhunen E, Kantelinen A, Niku-Paavola M L
VTT, Biotechnical Laboratory, Espoo, Finland.
Arch Biochem Biophys. 1990 May 15;279(1):25-31. doi: 10.1016/0003-9861(90)90458-b.
A homogeneous Mn-dependent peroxidase (MnP) was purified from the extracellular culture fluid of the lignin-degrading white rot fungus Phlebia radiata by anion exchange chromatography. The enzyme had a molecular weight of 49,000 and pI 3.8. It was a glycoprotein, containing carbohydrate moieties accounting for 10% of the molecular weight. Mn-peroxidase was capable of oxidizing phenolic compounds in the presence of H2O2, whereas the effect on nonphenolic lignin model compounds was insignificant. MnP contained protoporphyrin IX as a prosthetic group. During enzymatic reactions H2O2 converted the native MnP to compound II. Mn2+ was essential in completing the catalytic cycle by returning the enzyme to its native state. The oxidation of ultimate substrates was dependent on superoxide radicals, O2- and probably on Mn3+ generated during the catalytic cycle. MnP exhibited high activity of NADH oxidation without exogenously added H2O2. It was shown to produce H2O2 at the expense of NADH.
通过阴离子交换色谱法从木质素降解白腐真菌辐射脉菌的细胞外培养液中纯化出一种均一的锰依赖性过氧化物酶（MnP）。该酶分子量为49,000，等电点为3.8。它是一种糖蛋白，碳水化合物部分占分子量的10%。锰过氧化物酶在过氧化氢存在下能够氧化酚类化合物，而对非酚类木质素模型化合物的作用不明显。MnP含有原卟啉IX作为辅基。在酶促反应过程中，过氧化氢将天然MnP转化为化合物II。Mn2+通过使酶恢复到天然状态，对完成催化循环至关重要。最终底物的氧化依赖于超氧自由基O2-，可能还依赖于催化循环中产生的Mn3+。MnP在不添加外源过氧化氢的情况下表现出高活性的NADH氧化。结果表明它以NADH为代价产生过氧化氢。
