Study Of 2-Phenyl-4-Quinoline Carboxylic Acid Scaffold As A Two-face Bim BH3 α-Helix Mimetic

Proteins are the material basis of life activites, protein-protein interactions play a crucial role in cells growth, development, differentiation, apoptosis and other activites. The Bcl-2 family proteins are central regulators of apoptosis, through the interactions between the members of the Bcl-2 family proteins can promote or inhibit apoptosis, in order to maintain the balance of the organism.The Bcl-2 family proteins are divided into three classes, anti-apoptosis proteins, pro-apoptosis proteins and BH3-only proteins, represented by Bim. The a-helix of Bim (Bim BH3 a-helix) can be combined with the hydrophobic groove of the anti-apoptotic protein Mcl-1 and release and activation of the pro-apoptotic protein Bak, then, initiate the apoptosis program of downstream. In the Bim BH3 a-helix, the key amino acid residues for the combination of anti-apoptotic protein are called hotspots, these hotspots distribution in the two faces of the helix, respectively is 158, L62,165, D67 and F69. Simulation the hotspots of Bim BH3 a-helix by small molecules can occupy the groove of anti-apoptotic proteins, inducing the apoptosis of tumor cells.So far, small molecular design strategy of a-helix mimetics has two main types. One type is peptide mimetics, another kind is non-peptide mimetics. Peptide mimetics’cell membrance through rate is low and easy to hydrolysis by protease. Non-pepitide mimics mostly can only simulate the hotspots in hydrophobic face of the helix, but cannot mimic the hotspots in hydrophilic face including D67. That not only reduce the affnity of molecular simulation, but also reduce the protein targeting. This is a major botteneck of non-peptide mimetics in the research field.Through analysis the a-helix structure and distribution and spatial relative position of hotspots in Bim BH3 a-helix, we reasonable design the small molecular scaffold 4a which can simulate the two faces of a-helix.4a can bind Mcl-1 protein with Ki=1.98 μm and IC50=2.27 μm by biological experiments. On the basis of 4a, and according to the molecule design needs, we adapt the synthetic route that accord with the green chemistry and obtain a series of 2-phenyl-4-quinoline carboxylic acid derivatives. By fluorescence polarization experiments, ELISA experiments and MTT cell experiments confirming that 4d is the most effective small molecule to Mcl-1 protein in the series K;=0.579 μm and IC50=0.668 μm. Through all molecules structures and affinity compared, docking simulation and theoretical calculation, the results show 4d can simulate L62,165 and D67 three hotspots in two faces of Bim BH3 a-helix, has the conserved binding mode to Mcl-1, occupies the P2 and P3 pockets and formation of hydrogen bonds with R263, dissociates the Bcl-2 family protein-protein interaction in cells and induces apoptosis of tumor cells. Therefore,4d is a two faces Bim BH3 α-helix mimic...