中文摘要：

栓菌420（Trametes sp．420）漆酶基因lacD以两种方式在巴斯德毕赤酵母（Pichiapastoris）进行异源表达，产生两种重组漆酶：rLacDx（具有天然N-末端）和rLacDe（N-末端带有8个额外的氨基酸残基）。摇瓶发酵18d，rLacDx和rLacDe的产量分别为1．21×10^5u／L、7、38×10^4u／L[以2，2＇-连氮-3-乙苯-二噻唑-6磺酸（ABTS）为底物]。在高密度发酵条件下，rLacDx的产量增加到2．39×10^5u／L，同时其生产周期降至7．5d。两种重组酶对愈创木酚底物的氧化特性相似，且在50℃和pH3～10的范围内均稳定。然而，rLacDx对底物ABTS的比活力（1761u／mg）高于rLacDe（1122u／mg），其表观Km值（427μmol／L）低于rLacDe（604μmol／L）。

英文摘要：

A laccase gene （lacD） from the basidiomycete Trametes sp. 420 was heterologously expressed in Pichia pastoris in two ways, resulting in two recombinant enzymes of rLacDx with native N-terminus and rLacDe with eight additional amino acid residues at N-terminus. The yields of rLacDx and rLacDe in shaken-flask cultures after an 18-day growth were 1.21 × 10^5u/L and 7.38 × 10^4 u/L, respectively, as determined with 2,2＇-azinobis（3-ethylbenzothia-zoline- 6-sulfonic acid） （ABTS） as substrate. The yield of rLacDx was further increased to 2.39 × 10^5u/L under high-density fermentation while the production process was decreased to 7.5 days. In addition, rLacDx and rLacDe exhibited similar enzymatic characters in oxidizing substrate guaiacol, and were stable at 50℃ and at a pH range from 3 to 10. However, the specific activity of rLacDx （1,761u/mg） for ABTS was higher than that of rLaeDe （1,122u/mg）, and the apparent Km value of rLaeDx （427 μM） was less than that of rLaeDe （604 μM）.