摘要:
通過生物信息學(xué)分析、分子動(dòng)力學(xué)模擬及量子化學(xué)計(jì)算,對(duì)21種鄰對(duì)位取代酚類模式底物與漆酶的結(jié)合能力以及反應(yīng)活性進(jìn)行了探討.生物信息學(xué)結(jié)構(gòu)比對(duì)分析發(fā)現(xiàn)漆酶的活性口袋含有 Asp/Glu206, Asn/His208, Asn264, Gly392和His458等保守的氨基酸殘基(氨基酸殘基編號(hào)以Trametes versicolor漆酶為例, PDB:1KYA);采用MM-GBSA方法計(jì)算了21種酚類模式底物與T. versicolor漆酶的結(jié)合自由能.分子力學(xué)計(jì)算結(jié)果表明,漆酶與底物的結(jié)合力主要來自Asp206和Asn264等殘基與底物分子形成的分子間氫鍵,并且Phe265殘基和酚類底物的芳香環(huán)形成仔-仔相互作用.量子化學(xué)計(jì)算表明,芳環(huán)上取代基的推拉電子效應(yīng)顯著影響協(xié)同電子轉(zhuǎn)移的底物去質(zhì)子化過程,其中推電子能力較強(qiáng)的-NH2,-OH,-OCH3和-CH CHCH3等基團(tuán)能夠明顯增強(qiáng)酚羥基反應(yīng)活性,而吸電子的-CONH2和-Cl則具有相反的效應(yīng).%The binding affinity and reactivity between laccase and phenolic substrates were investigated with bioinformatics analysis, molecular dynamics simulation and quantum chemical calculation. Sequence and structure alignments indicate that the substrate-binding pocket of the laccases include certain conserved amino acid(AA) residues, such as Asp/Glu206, Asn/His208, Asn264, Gly392, His458(using the AA sequence number of PDB:1KYA, a laccase from Trametes versicolor). Accordingly, the binding affinity between the laccase and the modeled 21 phenolic substrates were calculated with the MM-GBSA method. As a result of the molecular modeling, the inter-molecular hydrogen bonding between the hydroxyl group and Asp206/Asn264, and theπ-πinteraction between the phenyl group and Phe265 , are essential for binding phenolic substrates to the laccase. The quantum chemistry calculations indicate that electronic effects of the additional substituent groups on the substrates would affect reductivity significantly, in particular for the collaborative deprotonation. The electron-donating groups, such as-NH2 ,-OH,-OCH3 and-CH CHCH3 , enhance the substrate reactivity, while the electron-withdrawing groups not, e. g. C( O) NH2 and-Cl. Our theoretical studies revealed that the binding affinity and reactivity stem from the different physiochemical nature, casting funda-mental insights to future molecular design of laccase-mediator system.