STRUCTURE OF ANTIBODY COMPLEXES WITH BIOACTIVE PEPTIDES

小肽激素的极端灵活性阻碍了对 阐明其溶液结构。 其受体的结构研究 结合构象也是不可能的， (for它们是复杂的、完整的膜蛋白。 因此，重要的问题，高亲和力识别的小， 柔性肽激素仍然是难以捉摸的。 在这个项目中， 对两种肽激素的复合物进行结构研究-- 血管紧张素II和促性腺激素释放激素-高亲和力 克隆抗体 这些研究旨在了解所有 激素的高亲和性识别方面， 从结构数据评价材料性能。 在 此外，结构信息将用于类似物的设计 可以结合抗体的激素（可能是天然的 受体）具有高亲和力。 作为这个项目的一部分，我们决定 测量的Fab/All复合物（Fab-131）的三维结构 结合的热力学，发展了预测亲和力的方法， 根据结构信息，并确定了几个成员， 结合抗体的组合环肽文库。 在 下一阶段我们建议：1）确定和完善 Fab 131与AII类似物的复合物-包括环肽， 鉴定AII和AII拮抗剂; 2）设计和表征新的AII 对Fab-131具有潜在的高亲和力的类似物; 3）以完成 Fab 110-AII复合物的结构测定和分析 结合的能量学。 测定Δ G、Δ H， 结合的δ Cp和δ S; 4）确定结合的结构。 AII和AII类似物与Fab-133、Fab-110和Fab-A25的复合物; 5）至 使与AII和GnRH复合的其它Fab片段结晶。

The extreme flexibility of small peptide hormones has hindered attempts at elucidating their solution structure. Structural studies of their receptor bound conformations have not been possible either because the receptors (for those that they are known) are complex, integral membrane proteins. Thus, important questions about high affinity recognition of small, flexible peptide hormones have remained elusive. In this project awe are carrying out structural studies on complexes of two peptide hormones -- angiotensin II and gonadotrophin releasing hormone-- with high affinity monoclonal antibodies. These studies are directed at understanding all aspects of high affinity recognition of the hormones including the evaluation of thermodynamical properties from structural data. In addition, the structural information will be used in the design of analogs of the hormones that could bind the antibodies (and may be the natural receptors) with high affinity. As part of this project we have determined the three dimensional structure of a Fab/All complex (Fab-131), measured the thermodynamics of binding, developed methods that predict affinities based on structural information, and identified several members of a combinatorial cyclic peptide library that bind to the antibody. In the next period we propose: 1) to determine and refine the structures of the complexes of Fab 131 with AII analogs --including the cyclic peptides we identified-- and AII antagonists; 2) to design and characterize new AII analogs with potential high affinity for Fab-131; 3) to complete the determination of the structure of the Fab 110-AII complex and the analysis of the energetics of binding. Determination of the deltaG, deltaH, deltaCp, and deltaS of binding; 4) to determine the structure of the complexes of AII and AII analogs with Fab-133, Fab-110 and Fab-A25; 5) to crystallize other Fab fragments complexed to AII and GnRH.