In vitro treatment of dioxins by enzymes from white-rot fungus.

用白腐菌Ceriporia sp.菌株MZ-340培养液孵育，观察到2,7-二氯二苯并对二恶英（diCDD）的回收率降低。在180min的时间内，采收率下降了50uM的40%。在煮沸对照中，diCDD的回收率可达90%以上。未回收的diCDD残留在水层中，可通过酸、碱或表面活性剂处理反应混合物回收。通过蛋白酶处理和加热，这种双氯丁二烯捕获活性丧失了。我们对真菌胞外蛋白溶液（EPs）的dicdd捕获活性进行了表征。pH值为2.7时活性最佳。在25-45℃范围内观察到80%以上的最大活性。这种活性随着孵育温度的升高而急剧下降。在有机溶剂浓度的影响下，分别加入5.0%的丙酮和12.5%的N，N-二甲基甲酰胺使活性消失。通过捕集活性检测底物特异性。对二苯并呋喃（DF）、联苯（BP）、二苯并噻吩、咔唑、芴、二苯基醚和菲的捕集活性较低或无捕集活性。以diCDD的捕集率表示时，triCDD、diCDF、diCBP和蒽的捕集率均在50%以上，而DD、monoCDD和tetraCDD的捕集率均低于40%。这些结果表明，捕获活性的特异性取决于底物的疏水性。此外，浓缩的EPs甚至可以捕获octaCDD。

The decrease of 2,7-dichlorodibenzo-p-dioxin (diCDD)-recovery was observed by the incubation with the culture fluid from white-rot fungus Ceriporia sp.strain MZ-340. The decrease of recovery reached 40% of 50uM during 180min period. The recovery of diCDD in the boiled control was higher than 90%. Not recovered diCDD was remained in the water layer, and it was retrievable by treating reaction mixture by acid, alkali or surfactant. Such diCDD-trapping activity was lost by a protease treatment and heating.We characterized the diCDD-trapping activity of the extracellular protein solution (EPs) from the fungus. The pH optimum of the activity was obtained at pH 2.7. More than 80% of the maximal activity was observed within a range of 25-45℃. This activity decreased dramatically as the incubation temperature increased. In the effects of organic solvent concentrations, the activity was disappeared by the addition of 5.0% of acetone or 12.5% of N,N-dimethylformamide, respectively.The substrate specificity was examined on the trapping-activity. Less or no trapping activity was observed for dibenzofuran (DF), biphenyl (BP), dibenzothiophene, carbazole, fluorene, diphenyl ether and phenanthrene. The trapping-activity for triCDD, diCDF, diCBP and anthracene showed over 50%, and that for DD, monoCDD and tetraCDD were lower than 40%, when their rates were expressed as percentages of the activity for diCDD.These results showed that the specificity of the trapping activity depends on the hydrophobicity of the substrate.Furthermore, the concentrated EPs could trap even octaCDD.