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

白腐菌Ceriporia sp.MZ-340菌株的培养液对2，7-二氯二苯并-对二恶英(DiCDD)的回收率降低。在180min内，回收率下降到50uM的40%。煮沸对照的回收率大于90%。未回收的DiCDD残留在水层中，用酸、碱或表面活性剂处理反应混合物可回收。这种捕获二CDD的活性被蛋白酶处理和加热而丧失。我们表征了来自真菌的胞外蛋白溶液(EPs)的捕获二CDD的活性。该酶的最适pH为2.7。在25-45℃范围内观察到80%以上的最大活性。随着孵化温度的升高，该酶活性急剧下降。在有机溶剂浓度的影响下，分别加入5.0%的丙酮或12.5%的N，N-二甲基甲酰胺，酶活消失，底物专一性考察了酶的捕集活性。对二苯并呋喃(DF)、联苯(BP)、二苯并噻吩苯、咔唑、荧烯、二苯醚和菲的捕集活性较低或没有。以对二环糊精的截留率表示，三环糊精、二环糊精、二环芳烃和菲的截留率均在50%以上，而对二环芳烃、单环糊精和四环糊精的截留率均低于40%。结果表明，截获活性的特异度取决于底物的疏水性。

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.