Hammel K E, Kalyanaraman B, Kirk T K
J Biol Chem. 1986 Dec 25;261(36):16948-52.
The lignin peroxidase (ligninase) of Phanerochaete chrysosporium catalyzes the oxidation of a variety of lignin-related compounds. Here we report that this enzyme also catalyzes the oxidation of certain aromatic pollutants and compounds related to them, including polycyclic aromatic hydrocarbons with ionization potentials less than or equal to approximately 7.55 eV. This result demonstrates that the H2O2-oxidized states of lignin peroxidase are more oxidizing than the analogous states of classical peroxidases. Experiments with pyrene as the substrate showed that pyrene-1,6-dione and pyrene-1,8-dione are the major oxidation products (84% of total as determined by high performance liquid chromatography), and gas chromatography/mass spectrometry analysis of ligninase-catalyzed pyrene oxidations done in the presence of H2(18)O showed that the quinone oxygens come from water. We found that whole cultures of P. chrysosporium also transiently oxidize pyrene to these quinones. Experiments with dibenzo[p]dioxin and 2-chlorodibenzo[p]dioxin showed that they are also substrates for ligninase. The immediate product of dibenzo[p]dioxin oxidation is the dibenzo[p]dioxin cation radical, which was observed in enzymatic reactions by its electron spin resonance and visible absorption spectra. The cation radical mechanism of ligninase thus applies not only to lignin, but also to other environmentally significant aromatics.
黄孢原毛平革菌的木质素过氧化物酶（木质素酶）催化多种与木质素相关的化合物的氧化反应。在此我们报告，该酶还能催化某些芳香族污染物及其相关化合物的氧化，包括电离电位小于或等于约7.55 eV的多环芳烃。这一结果表明，木质素过氧化物酶的H2O2氧化态比传统过氧化物酶的类似氧化态氧化性更强。以芘为底物的实验表明，芘-1,6-二酮和芘-1,8-二酮是主要氧化产物（通过高效液相色谱法测定，占总量的84%），并且在H2(18)O存在下对木质素酶催化的芘氧化反应进行气相色谱/质谱分析表明，醌氧来自水。我们发现黄孢原毛平革菌的全细胞培养物也能将芘短暂氧化为这些醌类物质。以二苯并[p]二恶英和2-氯二苯并[p]二恶英为底物的实验表明，它们也是木质素酶的作用底物。二苯并[p]二恶英氧化的直接产物是二苯并[p]二恶英阳离子自由基，在酶促反应中通过其电子自旋共振和可见吸收光谱观察到了该自由基。因此，木质素酶的阳离子自由基机制不仅适用于木质素，也适用于其他对环境有重要意义的芳烃。
