登革热是由登革热病毒（DENV1-4）感染引起的急性传染病，至今没有有效的疫苗和抗病毒药物。登革热病毒蛋白酶NS2B-NS3p属于丝氨酸蛋白酶，通过切割病毒前体多肽链而在病毒成熟过程中扮演着关键作用，被广泛看作有效的抗病毒靶标。DENV2蛋白酶NS2B-NS3p非活性形态的晶体结构已被解析，但晶体学方法（包括本实验室多年的工作）一直未能获得其活性构象的结构，因此其分子水平的酶催化机制仍不清楚，基于结构的抗病毒药物研发也就缺乏有效的模型。本项目选取广谱的丝氨酸蛋白酶抑制剂BPTI，旨在通过以溶液状态的样品为研究载体的核磁共振技术解析DENV2 NS2B-NS3p的活性结构，阐释其酶催化机理，为以该蛋白为靶标的抗登革热病毒药物的研发奠定坚实的理论基础。我们已经用NMR检测到DENV2 NS2B-NS3p与BPTI的相互作用，显示出良好的稳定结的稳定结构，为本项目的顺利开展提供了重要的保证。

Dengue fever was caused by infection of Dengue virus, including four different serotypes (DENV1-4). Without effective vaccine and anti-viral drugs, it is estimated that more than 50 million populations are infected with a mortality of 5% every year. NS2B-NS3p is a trypsin-like serine protease, and plays a critical role in the process of virus maturation by processing the polypeptide chain, therefore it is widely regarded as a target for antivirus drug discovery. The crystal structure of DENV2 NS2B-NS3p in its inactive form has been determined. However, the mechanism is little known due to the lack of structural information for its active form, including our many years failed attempts to obtain the crystal structures. It is therefore difficult to guide the effective antiviral drug discovery against NS2B-NS3p. In this study, we aim to determine the solution structure of NS2B-NS3p in the presence of BPTI using NMR. Combining with the inactive crystal structure, this solution study will elucidate the catalysis mechanism for this enzyme. This will shed light on the design of antiviral drug against DENV2 NS2B-NS3p. Our preliminary results using NMR have confirmed the interactions between NS2B-NS3p and BPTI, with an increased dispersion of peak of NS2B-NS3p induced by the addition of BPTI. These data indicate that the structure of NS2B-NS3p is stable in the presence of BPTI. These data will greatly facilitate our proposed structural study of this enzyme detailed in this proposal.