Kinetic and thermodynamic insights into interaction of albumin with piperacillin: Spectroscopic and molecular modeling approaches

The current study investigated the binding of BSA and piperacillin at multifarious concentrations (1 e128 mM) along with four different temperatures. To do this, three sensitive methods were employed including surface plasmon resonance (SPR), fluorescence spectroscopy and molecular docking (MD). In the SPR method, BSA immobilized on the carboxymethyl dextran (CMD) hydrogel sensor chip through NHS/EDC activation. The Van’t Hoff equation was applied for thermodynamic parameters determination at four distinct temperatures. Fluorescence spectroscopy results showed that binding constants decrease upon BSA interaction with piperacillin by rising temperature, which is indicative of BSA-piperacillin’s complex formation and fluorescence quenching mechanism of BSA induced by piperacillin is via both static and dynamic quenching process. The SPR analysis showed dose-response sensorgrams of BSA as piperacillin concentration increased. In this regard, piperacillin demonstrated a higher affinity to BSA that was concluded via a smaller amount of equilibrium constants (KD). Besides, docking results indicated that IB and IIIA subdomains of BSA are the most favorable sites for piperacillin binding. Therefore, the attained results showed that piperacillin interaction with BSA could be changed from van der Waals interactions to hydrogen bonds depending on the BSA subdomains.