基于分子动力学模拟与实验验证探讨黄芩素抑制PD-1/PD-L1相互作用的分子机制OACSTPCD

To study the molecular mechanism of baicalein interrupting the programmed cell death-1(PD-1)and progra-mmed cell death-ligand 1(PD-L1)pathway,molecular docking,molecular dynamics simulation,binding free energy calcu-lation and principal component analysis were first performed to predict the inhibition effect of baicalein on this pathway,which was verified by enzyme-linked immunosorbent assay(ELISA)subsequently.Binding free energy calculations show-ed that the affinity of baicalein to the PD-L1 dimer was-32.41±0.31 kcal/mol.Free energy decomposition,contact numbers and nonbonded interaction results revealed that baicalein mainly interacted with the C-,C'-,F-and G-sheet domains of the PD-L1 dimer.Importantly,nonpolar interactions between the key residues Tyr56,Met115,Ala121,Asp122 and baicalein were dominant factors during the binding process.Cross-correlation matrixes and secondary structure results further demo-nstrated that baicalein could stably interact with the sheet domains of the PD-L1 dimer.The result of ELISA showed that the IC50 value of baicalein for inhibiting the PD-1/PD-L1 interaction was 79.47µg/L.In conclusion,this study revealed that baicalein could directly bind to the PD-L1 dimer,thus blocking the PD-1/PD-L1 interaction,would provide basis for discovering natural small-molecule inhibitors of this pathway.