Exploring Key Orientations of Small Molecules to Disrupt Protein-protein Interactions

摘要

Protein-protein interactions (PPIs) are attractive targets because of their therapeutic potential. One approach to design small molecules that can disrupt the PPIs is to use structural information of proteins. With this approach, triazole-based peptidomimetics that mimic beta-turn hot-spot regions in neurotrophins were synthesized. The monovalent mimics were assembled into bivalent mimics via a combinatorial method. Three different bivalent mimics were prepared for different studies. Bivalent mimics with long-linkers bound to TrkA or TrkC receptor and showed partial antagonism for the receptors. Other mimics were conjugated with cytotoxic compounds and they were used for TrkC targeted drug delivery. The last group of bivalent mimics previously showed targeted delivery effects for pancreatic cancer cells. In this study, we synthesized Eu-chelated bivalent mimics to perform a competitive binding assay for pancreatic cancer cells. Previous research in our group focused on design of secondary structures' mimics on rigid scaffolds as "minimalist mimics." We sought to establish structural design criteria for the minimalist mimics, and we wanted to propose that sets of such compounds could mimic local pairs of amino acids in any secondary structures as "universal peptidomimetics." Thus, we designed five compounds, such as oxazoline-, pyrrole-, dyine- "kinked" and "linear" bistrizole-based peptidomimetics, and performed molecular modelings, DFT calculations, and QMD for them to validate our hypothesis. On the concepts of "minimalist mimics" and "universal peptidomimetics," we developed the C alpha ? C beta vector matching program to evaluate preferred orientations of C alpha - C beta coordinates for secondary structures. We applied the program to omegatides and pyrrolinone-pyrrolidine oligomers. The compounds matched better with strands than for helices. We expanded the C alpha ? C beta vector matching idea to a method that ranks preferred conformations of small molecules on any combination of three interface side-chains in all structurally characterized PPIs. We developed a PDB mining program (explores key orientation, EKO) to do this, and EKO applied to pyrrolinone-pyrrolidine oligomers to find targets. EKO found several interesting targets, such as AICAR Tfase, GAPDH, and HIV-1 protease. HIV-1 dimerization inhibition and Zhang-Poorman kinetic assays were performed to validate our hypothesis, and the results showed that pyrrolinone-pyrrolidine derivatives inhibited HIV-1 dimerization.