Comprehensive views toward the biomolecular recognition of an anticancer drug, leflunomide with human serum albumin

Abstract

Biomolecular association of an anticancer drug, leflunomide (LEF) with human serum albumin (HSA), the leading ligands carrier in human circulation was characterized using biophysical (i.e., fluorescence, absorption and voltammetric) methods and computational (i.e., molecular docking and molecular dynamics simulation) techniques. Evaluations of fluorescence, absorption and voltammetric findings endorsed the complex formation between LEF and HSA. An inverse relationship of Stern-Volmer constant–temperature and hyperchromic shift of the protein’s absorption signal with addition of LEF confirmed the LEF quenched the HSA fluorescence through static process. Moderate nature of binding strength (binding constant = 2.76–4.77 × 10⁴ M⁻¹) was detected towards the LEF–HSA complexation, while the association process was naturally driven via hydrophobic interactions, van der Waals interactions and hydrogen bonds, as evident from changes in entropy (ΔS= + 19.91 J mol⁻¹ K⁻¹) and enthalpy (ΔH = − 20.09 kJ mol⁻¹), and molecular docking assessments. Spectral analyses of synchronous and three-dimensional fluorescence validated microenvironmental fluctuations near Trp and Tyr residues upon LEF binding to the protein. LEF association with HSA significantly defended temperature-induced destabilization of the protein. Although LEF was found to attach to HSA at Sudlow’s sites I and II, but exhibited greater preference toward its site I, as detected by the investigations of competitive site-marker displacement. Molecular dynamics simulation assessment revealed that the complex attained equilibrium throughout simulations, showing the LEF–HSA complex constancy.

Communicated by Ramaswamy H. Sarma

Schemkatic views of LEF–HSA Interaction

Keywords:

• leflunomide
• human serum albumin
• ligand–protein interaction
• biophysical methods
• computational techniques

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The Scientific and Technological Research Council of Türkiye (TÜBİTAK) provided Research Grant for this work. It is highly appreciated that Md. Zahirul Kabir received financial support from TÜBİTAK in the form of Research Fellowship [2236-TÜBİTAK project number: 121C051] through the Co-Funded Brain Circulation2 Scheme (CoCirculation2).