Metabolic mechanisms involved in hydroxylation reactions of diphenyl compounds by the lignin-degrading basidiomycete Phanerochaete chrysosporium
Metabolic mechanisms involved in hydroxylation reactions of diphenyl compounds by the lignin-degrading basidiomycete Phanerochaete chrysosporium
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DOI：
10.1016/j.bej.2005.01.008
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发表时间：
2005-05-01
影响因子：
3.9
通讯作者：
Wariishi, H
中科院分区：
文献类型：
--
作者：
Hiratsuka, N;Oyadomari, M;Wariishi, H
联苯 (BP)、联苯撑 (BN)、二苯并呋喃 (DF)、二苯并对二恶英 (DD) 和二苯醚 (DE) 被用作木质素降解担子菌、黄孢原毛平革菌 (Phanerochaete chrysosporium) 及其胞外酶木质素过氧化物酶 (LiP) 的联苯底物。在这些化合物中，只有BN和DD被LiP氧化。循环伏安法测量表明，BN 和 DD 比其他使用的二苯基底物具有更低的氧化还原电位，这与 LiP 的反应性一致。尽管 BP、DF 和 DE 的降解不是由 LiP 在细胞外引发的，但它们是通过细胞内酶形成的羟基化产物的中间体进行代谢的。添加细胞色素 P450 抑制剂胡椒基丁醚后，这些羟基化反应被有效抑制，表明细胞色素 P450 的参与。因此，黄孢假单胞菌代谢多种顽固联苯化合物似乎必须有两种单独的机制：一种是通过LiP催化单电子氧化形成芳基阳离子自由基来活化芳环，另一种是通过细胞色素P450酶活化分子氧，引起芳环上的羟基化反应。 (c) 2005 年 Elsevier B.V. 出版
Biphenyl (BP), biphenylene (BN), dibenzofuran (DF), dibenzo-p-dioxin (DD), and diphenyl ether (DE) were utilized as diphenyl substrates for the lignin-degrading basidiomycete, Phanerochaete chrysosporium and its extracellular enzyme, lignin peroxidase (LiP). Among these compounds, only BN and DD were oxidized by LiP. Cyclic voltarnmetry measurement revealed that BN and DD possess lower redox potentials than other diphenyl substrates utilized, being accordance with a reactivity of LiP. Although the degradations of BP, DF and DE were not extracellularly initiated by LiP, they were metabolized via an intermediate formation of hydroxylated products by intracellular enzymes. Upon addition of piperonyl butoxide, a cytochrome P450 inhibitor, these hydroxylation reactions were effectively inhibited, indicating the involvement of cytochrome P450s. Thus, two individual mechanisms seem to be compulsory for P. chrysosporium to metabolize a wide variety of recalcitrant diphenyl compounds; one is the activation of the aromatic ring via LiP catalyzed one-electron oxidation forming the aryl cation radical and the other is the activation of molecular oxygen by cytochrome P450 enzymes causing hydroxylation reactions on the aromatic ring. (c) 2005 Published by Elsevier B.V.