Analysis of the interaction behavior between Nano-Curcumin and two human serum proteins: combining spectroscopy and molecular stimulation to understand protein-protein interaction.

In this study, we have investigated the effects of Nano-curcumin (Nano-CUR) binding on HSA-HTF interactions as binary and ternary systems, which had been done through multiple spectroscopic and MD simulation. It has been indicated by fluorescence spectroscopy that Nano-CUR is capable of quenching both proteins with a static mechanism. Thermodynamic parameters have been calculated by considering the fluorescence data at different temperatures. The binding constants of HSA-Nano-CUR, HTF-Nano-CUR and (HSA-HTF) Nano-CUR complexes formation were (2.03 ± 0.32)×107 M-1, (2.46 ± 0.32)×106 and (4.54 ± 0.32)×106 M-1 respectively. According to the negative values of ΔH0 and ΔS0, the roles of van-der-Waals forces and hydrogen bond are quite essential throughout this particular binding. Besides, the negative ΔH0 and ΔS0 values of HTF (Nano-CUR) have been larger than those of the HSA (Nano-CUR) and HSA-HTF (Nano-CUR), which demonstrates the higher significance of interaction bonding. As it had been detected through the synchronized fluorescence spectroscopy at Δλ = 60 nm, the position of Nano-CUR with mixed protein in ternary system has been closer to Tyr residues. Relatively, the binding distances between Trp residues of HSA and HTF in HSA (Nano-CUR), HTF (Nano-CUR), and (HSA-HTF Nano-CUR) complexes, which had been procured in accordance with the fluorescence resonance energy transfer (FRET), have been found to be 1.82 nm, 1.87 nm, and 1.92 nm, respectively. We have evaluated the induced conformational changes of two proteins throughout the binding of Nano-CUR to HSA and HTF as binary and ternary systems by employing the CD technique, while the formation of self-assemblies has been studied through MD simulation.