Exploring molecular recognition between an anti-neoplastic drug, floxuridine, and human serum albumin through spectroscopic, computational and atomic force microscopic approaches / Fazal Rehman

Fazal , Rehman (2023) Exploring molecular recognition between an anti-neoplastic drug, floxuridine, and human serum albumin through spectroscopic, computational and atomic force microscopic approaches / Fazal Rehman. Masters thesis, Universiti Malaya.

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Abstract

The binding mode of antineoplastic antimetabolite, floxuridine (FUDR), with human serum albumin (HSA), the leading carrier in blood circulation, was ascertained using multi-spectroscopic, microscopic, and computational techniques. A static fluorescence quenching was established due to decreased Ksv values with rising temperatures, suggesting FUDR-HSA complexation. UV-vis absorption spectral results also supported this conclusion. The binding constant, Ka values, were found within 9.6−7.9  103 M−1 at 290, 300, and 310 K, demonstrating a moderate binding affinity for the FUDR-HSA system. Thermodynamic data (Sº = +46.35 J.mol−1.K−1 and, Hº = −8.77 kJ.mol−1) predicted the nature of stabilizing forces (hydrogen-bonds, hydrophobic, and van der Waals interactions) for the FUDR-HSA complex. Circular dichroism spectra displayed a minor disruption in the protein’s 2o and 3o structures. At the same time, atomic force microscopy images proved variations in the FUDR-HSA surface morphology, confirming its complex formation. The protein's microenvironment around Trp/Tyr residues was also modified, as judged by 3-D fluorescence spectra. FUDR-bound HSA showed better resistance against thermal stress. As disclosed from ligand displacement studies, the FUDR binding site was placed in subdomain IIA (Site I). Further, the molecular docking analysis corroborated the competing displacement studies. Molecular dynamics evaluations revealed that the complex achieved equilibrium during simulations, confirming the FUDR–HSA complex's stability.

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