Study On The Intermolecular Interaction Of HIV-1 Protease Inhibitors With Biomacromolecules

The develpoment of HIV-1 protease inhibitors（HIV-1 PIs）and its utilization in highly active antiretroviral therapy（HAART）have dramaticallydecreasedacquiredimmunodeficiencysyndrome（AIDS）-related mortality.In this thesis,we probed the intermolecular interaction of three HIV-1PIs,Darunavir（DRV）,Ritonavir（RTV）and Lopinavir（LPV）with calf thymus deoxyribonucleic acid（ct-DNA）in physiological buffer（pH 7.4）by multi-spectroscopic methods in combination with viscosity measurements and molecular modeling techniques.The presented results suggested that HIV-1 PIs bound to ct-DNA with the binding constant（K_b）of the order of 10³ M^-1 mainly stabilized by van der Waals force and hydrogen bonds.A series of experiments including viscosity measurements,competitive binding investigations and circular dichroism spectral analysis revealed the groove binding nature of HIV-1 PIs with ct-DNA.Moreover,molecular simulation studies indicated that HIV-1 PIs were prone to bind in the A-T rich DNA fragments.The binding characteristics of three HIV-1 PIs（DRV,RTV and LPV）with bovine serum albumin（BSA）has been studied by multi-spectroscopic methods and molecular modeling techniques.Fluorescence data analysis revealed that HIV-1 PIs quenched the intrinsic fluorescence of BSA through a static（DRV and RTV）or combined dynamic and static quenching manner（LPV）.The UV absorption spectral results showed that there was weak binding ability of HIV-1 PIs（K_b was 10³-10⁴ orders of magnitude）in a single binding site on BSA.Based on the thermodynamic analysis,van der Waals force and hydrogen bonds played a predominant role in the binding reaction,and besides,hydrophobic interactions should not be dismissed.Molecular modeling validated the results obtained from the competitive binding experiments,DRV preferentially fit into the interface between sub-domain IIA and IIB of BSA（site II’）,RTV and LPV bound to the hydrophobic pocket in sub-domain IIIA of BSA（site II）.Additionally,synchronous and three-dimensional fluorescence spectral results indicated that the polarity surrounding the fluorophore was retained upon HIV-1 PIs interaction.Perturbation in the secondary structures of BSA in the presence of HIV-1 PIs was observed from fourier transform infrared（FT-IR）spectral analysis.