Beta Secretase Inhibition for Treating Alzheimer's Disease

描述(申请人提供)：Memapsin 2(β-分泌酶，BACE)是一种启动β-淀粉样前体蛋白(APR)裂解导致淀粉样β-β(Abeta)产生的蛋白酶。它是开发抗阿尔茨海默病(AD)抑制剂药物的主要靶点。了解Memapsin 2的活性、结构和功能是设计和测试抑制剂的基础。在这个项目的最后5年里，我们已经建立了检测方法，完成了动力学特异性分析，确定了晶体结构，并设计了几代抑制剂，这些抑制剂与选定的人天冬氨酸蛋白酶、细胞通透性和抑制转基因AD小鼠的Abeta产生相比，获得了高效、相对较小的尺寸和良好的选择性。在本项目的下一阶段，我们建议进一步探索Memapsin 2与抑制剂开发相关的结构-功能信息，以获得更好的类药物性质，探索新的抑制剂合成化学，并开发针对新发现的Memapsin 2亚基的非过渡态抑制剂。目的：1.深入开展Memapsin 2结构功能研究，为进一步基于结构的抑制剂设计奠定基础。我们建议研究新的配体与Memapsin 2亚基S7、S6和S5的结合亲和力，活性部位裂解“瓶颈”残基对抑制物亚基专一性的作用，Memapsin 2抑制剂对细胞的抑制作用，以及Memapsin 2抑制剂药物的治疗限度。目的2.设计和测试具有更好体内效力和选择性的过渡态Memapsin 2抑制剂。我们建议优化先导肽类抑制剂的配体结合部位的相互作用，设计和合成新型非肽高亲和力配体、模板和支架，结合碱性胺和亲脂功能以有效吸收和转运血脑屏障，并提高小分子非肽类抑制剂的效力。目的3.开发和测试针对蛋白水解酶中新位点的新型Memapsin 2抑制剂。我们建议设计和测试一类新的针对P7、P6和P5亚基的非过渡态抑制剂。我们将利用基于结构的设计周期来开发小的、有效的和选择性的新抑制剂。

DESCRIPTION (provided by applicant): Memapsin 2 (beta-secretase, BACE) is the protease that initiated the cleavage of beta-amyloid precursor protein (APR) leading to the production of amyloid-beta (Abeta). It is the major target for the development of inhibitor drugs against Alzheimer's disease (AD). The understanding on the activity, structure and function of memapsin 2 is fundamental for inhibitor design and testing. During the last 5 years of this project, we have established assays, completed kinetic specificity analysis, determined crystal structures and designed generations of inhibitors that have attained high potency, relatively small size, and good selectivity vs. chosen human aspartic proteases, cell permeability and inhibition of Abeta production in transgenic AD mice. For the next period of this project, we propose to further probe memapsin 2 for structure-function information relevant to inhibitor development, to acquire better drug-like properties, to explore new chemistry for inhibitor synthesis and to develop non-transition state inhibitors against newly discovered subsites of memapsin 2. The Aims are: Aim 1. To carry out in-depth memapsin 2 structure-function studies for further structure-based inhibitor design. We propose to investigate the binding affinity of new ligands toward memapsin 2 subsites S7, S6 and S5, the role of active-site cleft 'bottleneck' residues on the inhibitor subsite specificity, cellular inhibition by memapsin 2 inhibitors and the therapeutic limits of memapsin 2 inhibitor drugs. Aim 2. Design and testing transition-state memapsin 2 inhibitors with better in vivo potency and selectivity. We propose to optimize ligand-binding site interactions of lead peptidomimetic inhibitors, design and synthesize novel nonpeptidyl high-affinity ligands, templates and scaffolds, incorporate basic amines and lipophilic functionalities for effective absorption and BBB transport, and improve potency of small molecule nonpeptidyl inhibitors. Aim 3. To develop and test novel memapsin 2 inhibitors targeting to new sites in the protease. We propose to design and test a new class of non-transition state inhibitors targeted at 3 unique subsites, P7, P6 and P5. We will use structure-based design cycle to develop small, potent and selective new inhibitors.