【摘要】 淀粉蔗糖酶(amylosucrase,AS)以蔗糖为唯一底物和能量来源催化合成直链葡聚糖。与AS相比,其它拥有合成直链淀粉样多糖的酶都需要利用昂贵的核苷酸激活糖来进行合成。这使得AS成为一种具有工业应用潜力的工业酶。尽管具有较大应用潜力,但AS较弱的稳定性严重影响了其在工业上的应用。作者对在Deinococcus radiodurans中发现的一种AS(DrAS)的结构及功能进行了较深入的讨论。首先,利用高斯网络模型和各项异性网络模型对其功能型运动和工作机理进行预测。随后,利用迭代高斯网络模型方法对其去折叠路径进行了研究,所得结果可对随后的突变体设计工作提供有益的帮助。最后,根据去折叠路径预测及折叠自由能计算结果,对DrAS的稳定性改造提出了建议。更多还原

【Abstract】 Amylosucrase(AS) is a kind of glucosyltransferases.AS can catalyzes the synthesis of an amylose-like polysaccharide using sucrose as the only substrate and energy source.Unlike AS,other enzymes responsible for the synthesis of such amylose-like polymers require the addition of expensive nucleotide-activated sugars which makes AS an interesting enzyme for industrial applications.In spite of the great application potential,industrial applications of AS were largely hampered by its low stability.In this work,the structure and functions of a newly identified AS from Deinococcus radiodurans(DrAS) were thoroughly investigated.Firstly,the functional motions and working mechanism of DrAS were predicted by the Gaussian Network Model(GNM) and Anisotropic Network Model(ANM).Secondly,the iterative GNM method was applied to obtain the unfolding pathway of DrAS,which was quite helpful to the following design process.Finally,some helpful suggestions were proposed for stability engineering according to results of unfolding pathway and folding free energy predictions.更多还原