淀粉蔗糖酶AcAS的工作机理与去折叠性质研究(英文)  

Insights Into The Working Mechanism and Unfolding Property of Arthrobacter chlorophenolicus Amylosucrase

作　　者：刘明[1] 李平[2] 刘斌[3] 苏计国[4] 王存新[3] 

机构地区：[1]中国医学科学院北京协和医学院药物研究所,北京100050 [2]中国科学院过程工程研究所,北京100190 [3]北京工业大学生命科学与生物工程学院,北京100124 [4]燕山大学理学院,秦皇岛066004

出　　处：《生物化学与生物物理进展》2013年第6期565-577,共13页Progress In Biochemistry and Biophysics

摘　　要：淀粉蔗糖酶(amylosucrase,AS)是一种葡萄糖基转移酶(E.C.2.4.1.4),隶属于糖苷水解酶13家族.当体系中存在葡聚糖时,AS可以蔗糖为唯一底物催化合成直链葡聚糖.与AS相比,其他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,但是较弱的稳定性严重影响其在工业上的应用.本工作中,以NpAS和DgAS的晶体结构为模板,对氯酚节杆菌(Arthrobacter chlorophenolicus)中发现的一种新型AS(AcAS)结构进行了模建.通过对AcAS与其他AS结构进行详细的比较,推断出AcAS的工作机理.随后,利用高斯网络模型(GNM)对其功能型运动进行了分析.根据GNM的结果,发现AcAS可分为两个运动方向相异的部分.最后,利用迭代高斯网络对AcAS的去折叠性质进行了研究.这些结果对随后的淀粉蔗糖酶的工业开发有一定帮助.Amylosucrase （AS） is a kind of glucosyltransferase （E.C. 2.4.1.4） belonging to the glycoside hydrolase （GH） family 13. In the presence of an activator polymer, in vitro, AS is able to catalyze the synthesis of an amylose-like polysaccharide composed of only α-1,4-1inkages using sucrose as the only energy source. Unlike AS, other enzymes responsible for the synthesis of such amylose-like polymers require the addition of expensive nucleotide-activated sugars. These properties make 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 of A rthrobacter chlorophenolicus amylosucrase （AcAS） was modeled according to crystal structures of Neisseria polysaccharea amylosucrase （NpAS） and Deinococcus geothermalis amylosucrase （DgAS）. The structural difference of the three AS were investigated for the sake of exploring the working mechanism of AcAS. The dynamics and functional motions of AcAS were also investigated by the Gaussian network model （GNM）. Based on GNM, it was found that AcAS can be divided into two regions with different moving directions. Finally, the unfolding property of AcAS was studied by the iterative GNM, and several kinetically weak regions were identified on the basis of the predicted unfolding pathway. These discoveries may be helpful to the industrial development of AS.

关 键 词：淀粉蔗糖酶 同源模建 去折叠 高斯网络模型 迭代高斯网络模型 

分 类 号：Q6[生物学—生物物理学] Q51