Watanabe T, Koller K, Messner K
Laboratory of Biomass Conversion, Wood Research Institute, Kyoto University, Japan.
J Biotechnol. 1998 Jul 16;62(3):221-30. doi: 10.1016/s0168-1656(98)00063-7.
Thus far, it has not been recognized that copper complexes are able to depolymerize lignin under physiological conditions of white rot decay. However, we have found that both phenolic and non-phenolic synthetic lignins were intensively depolymerized by Cu(II) and lipid hydroperoxide model compounds in the presence of a metabolite of ligninolytic fungi, pyridine at room temperature in aqueous media. Treatment of 14C-labeled oxygen-prebleached kraft pulp (OKP) by the copper-dependent reaction evidenced effectiveness of this reaction for the delignification of kraft pulps. In contrast to the organic peroxide system, Cu(II)/pyr/H2O2 system was much less effective for the lignin depolymerization. However, treatment of unbleached kraft pulp (UKP) by Cu(II)/H2O2 and Cu(II)/pyr/H2O2 systems demonstrated that the damage of cellulose was suppressed by the coordination of pyridine although high brightness gain was obtained independently of the presence of the coordinator. Spin trapping experiments demonstrated that not hydroxyl radical but superoxide anion is involved in the Cu(II)/pyr/H2O2 system. This finding not only introduces a new concept of non-enzymatic lignin biodegradation by wood-degrading fungi but also presents a new strategy for decomposing lignin and lignin-related compounds by copper complexes and peroxide-producing system.
到目前为止，尚未认识到铜络合物能够在白腐菌腐朽的生理条件下使木质素解聚。然而，我们发现，在木质素分解真菌的一种代谢产物吡啶存在的情况下，在水介质中室温下，酚类和非酚类合成木质素都能被铜（II）和脂质氢过氧化物模型化合物强烈解聚。通过铜依赖反应处理14C标记的氧预漂硫酸盐浆（OKP）证明了该反应对硫酸盐浆脱木素的有效性。与有机过氧化物体系相比，铜（II）/吡啶/过氧化氢体系对木质素解聚的效果要差得多。然而，用铜（II）/过氧化氢和铜（II）/吡啶/过氧化氢体系处理未漂硫酸盐浆（UKP）表明，尽管无论有无配位剂都能获得高亮度增益，但吡啶的配位作用抑制了纤维素的损伤。自旋捕获实验表明，参与铜（II）/吡啶/过氧化氢体系的不是羟基自由基而是超氧阴离子。这一发现不仅引入了木材降解真菌非酶促木质素生物降解的新概念，而且还提出了一种利用铜络合物和过氧化物产生体系分解木质素及与木质素相关化合物的新策略。
