Exploring the interaction of bioactive kaempferol with serum albumin, lysozyme and hemoglobin: A biophysical investigation using multi-spectroscopic, docking and molecular dynamics simulation studies

In recent years research based on kaempferol (KMP) has shown its potential therapeutic applications in medicinal chemistry and clinical biology. Therefore, to understand its molecular recognition mechanism, we studied its interactions with the carrier proteins, namely, human serum albumin (HSA), bovine hemoglobin (BHb) and hen egg white lysozyme (HEWL). The ligand, KMP was able to quench the intrinsic fluorescence of these three proteins efficiently through static quenching mode. The binding constant (K-b) for the interactions of KMP with these three proteins were found in the following order: HSA-KMP > BHb-KMP > HEWL-KMP. Different noncovalent forces such as hydrogen bonding and hydrophobic forces played a major role in the binding of KMP with HSA and HEWL, whereas hydrogen bonding and van der Waals forces contribute to the complexation of BHb with KMP. KMP was able to alter the micro-environment near the Trp fluorophore of the proteins. KMP altered the secondary structural component of all three proteins. The putative binding sites and the residues surrounding the KMP molecule within the respective protein matrix were determined through molecular docking and molecular dynamics (MD) simulation studies. The conformational flexibility of the ligand KMP and the three individual proteins were also evident from the MD simulation studies.