漆酶降解阴离子型聚丙烯酰胺/聚丙烯酸酯活性的理性设计

为探究漆酶降解聚丙烯酸酯（PAA）/阴离子型聚丙烯酰胺（HPAM）的微观机理，采用对接模拟了其结构模型与枯草芽孢杆菌漆酶（B. subtilis laccase）的结合.根据-CDOCKER_Energy score打分最高的原则，对获得的最佳结合构象进行分析.然后基于亲和力虚拟氨基酸突变进行丙氨酸（ALA）扫描和饱和突变.结合模式分析表明，HPAM比PAA可更深地埋入活性口袋，B. subtilis laccase对HPAM的亲和力和结合能皆高于PAA.相互作用分析表明，疏水相互作用可能对B. subtilis laccase与底物的结合起到促进作用，而氢键作用会阻碍该酶与底物的结合.通过ALA扫描进一步得知，ARG487、GLY486和TYR133是B. subtilis laccase降解HPAM的关键氨基酸残基，而ASP113和TYR133是B. subtilis laccase降解PAA的关键氨基酸残基.通过饱和突变表明，ASP113>ARG可以提高B. subtilis laccase降解PAA的活性，这些数据为理性设计增强活性的B. subtilis laccase突变体提供了理论参考.

Rational design of degradation activity of anionic polyacrylamide/polyacrylate by laccase

In order to explore the degradation mechanism of anionic polyacrylamide (HPAM)/polyacrylate (PAA) by laccase, the docking was employed to investigate the binding modes of their structural model to Bacillus subtilis laccase (B. subtilis laccase). The optimal conformation was obtained and analyzed according to the highest principle of-CDOCKER_Energy score. Then, the alanine (ALA) scanning and saturated mutation were performed by the virtual amino acid mutation based on affinity. The analysis results of binding model showed that HPAM was buried deeper in the active pocket than PAA, and B. Subtilis laccase had higher affinity and binding energy with HPAM than PAA. The interaction analysis showed that the hydrophobic interaction may promote the binding of B. subtilis laccase to substrate, while the hydrogen bond could hinder their combination. It was further informed by the ALA scanning that the ARG487, GLY486 and TYR133 were the key amino acid residues of B. subtilis laccase degrading HPAM, while the ASP113 and TYR133 were the key amino acid residues in PAA degradation. The saturated mutation showed that the ASP113>ARG could enhance the activity of B. subtilis laccase degrading PAA. These data provided theoretical reference for rational design of B. subtilis laccase mutants with enhanced activity.