Insight into the interaction of benzothiazole tethered triazole analogues with human serum albumin: Spectroscopy and molecular docking approaches

The interaction of four benzothiazole tethered triazole analogues (MS43, MS70, MS71, and MS78) with human serum albumin (HSA) was investigated using various spectroscopic techniques (ultraviolet-visible (UV-vis) light absorption, fluorescence, circular dichroism (CD), molecular docking and density functional theory (DFT) studies). Fluorescence quenching constants (similar to 10(12)) revealed a static mode of quenching and binding constants (K-b similar to 10(4)) indicating the strong affinity of these analogues for HSA. Further alteration in the secondary structure of HSA in the presence of these analogues was also confirmed by far UV-CD spectroscopy. The intensity loss in CD studied at 222 nm indicated an increase in random coil/beta-sheet conformations in the protein. Binding energy values (MS71 (-9.3 kcal mol(-1)), MS78 (-8.02 kcal mol(-1)), MS70 (-7.16 kcal mol(-1)) and MS43 (-6.81 kcal mol(-1))) obtained from molecular docking revealed binding of these analogues with HSA. Molecular docking and DFT studies validated the experimental results, as these four analogues bind with HSA at site II through hydrogen bonding and hydrophobic interactions.