Purification and Characteristics of an Enzyme with Both Bilirubin Oxidase and Laccase Activities from Mycelium of the Basidiomycete Pleurotus ostreatus
Purification and Characteristics of an Enzyme with Both Bilirubin Oxidase and Laccase Activities from Mycelium of the Basidiomycete Pleurotus ostreatus
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DOI：
10.1134/s0006297909090119
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发表时间：
2009-09-01
影响因子：
2.8
通讯作者：
Lapko, A. G.
中科院分区：
文献类型：
--
作者：
Pakhadnia, Y. G.;Malinouski, N. I.;Lapko, A. G.
从担子菌平菇菌丝体的深层培养物中分离出具有胆红素氧化酶和漆酶活性的均质酶并进行了表征。酶的产量为127μg/g菌丝体干生物量。该酶对胆红素和漆酶底物 ABTS 的比活性分别为 21 和 261 U/mg。经鉴定，平菇菌丝体胞内酚氧化酶为胆红素氧化酶，其氨基酸序列与pox2基因编码产物高度同源。该酶在 50-55 摄氏度时对所有检测的底物显示出最大漆酶活性，而最适 pH 值取决于底物，从 ABTS 的 3.0 变为丁香醛连氮和愈创木酚的 7.0。该酶在较宽的 pH 范围内保持催化活性，但在 pH 4.0 时失活。该酶具有热稳定性，但对金属螯合抑制剂非常敏感。台盼蓝 (5 mg/L) 在室温下与胆红素氧化酶 (20 mU/ml) 一起孵育 3 小时后完全脱色。
A homogenous enzyme with both bilirubin oxidase and laccase activities was isolated from a submerged culture of the basidiomycete Pleurotus ostreatus mycelium and characterized. The yield of the enzyme was 127 mu g/g dry biomass of the mycelium. The specific activity of the enzyme was 21 and 261 U/mg to bilirubin and to a laccase substrate ABTS, respectively. The intracellular phenol oxidase from the P. ostreatus mycelium was identified as bilirubin oxidase with the amino acid sequence highly homologous to that of the pox2 gene-encoded product. The enzyme displayed the maximal laccase activity at 50-55 degrees C to all substrates examined, whereas the pH optimum was substrate-dependent and changed from 3.0 for ABTS to 7.0 for syringaldazine and guaiacol. The enzyme maintained catalytic activity within a broad pH range but was inactivated at pH 4.0. The enzyme was thermostable but very sensitive to metal chelating inhibitors. Trypan Blue (5 mg/liter) was completely decolorizated upon 3 h of incubation with the bilirubin oxidase (20 mU/ml) at room temperature.