Serum albumin-ligand interactions: Experimental and computational approaches

Biomolecular interactions, naturally occurring in living organisms, mediate most of the cellular functions, contribute to understanding the nature, function, and behavior of macromolecules, like proteins, and help to predict the biological processes involving macromolecules with unknown functions. Serum albumin (SA), the most important transport protein in the blood, has the capability to bind, covalently or reversibly, a great number of small endogenous and exogenous compounds. Structural changes in SA determine alterations in its biological function, and denaturation processes may affect both its secondary and tertiary structure levels. SA undergoes reversible conformational transitions in response to variations in pH and temperature, which in turn influence ligand binding. Binding events usually are coupled to other changes such as: folding, structural transitions, protonation, and other ligand-binding interactions. It is not sufficient to simply state that a molecule binds to SA. Understanding the binding process requires measurements of affinity, stoichiometry, and the elucidation of the driving forces of the binding. This review integrates experimental and computational approaches to characterize serum albumin-ligand interactions. Spectroscopic techniques, calorimetric methods, and other biophysical assays are discussed alongside with molecular docking and molecular dynamics simulations. By integrating experimental data with computational analyses, this paper aims to provide a comprehensive and coherent picture of the mechanisms underlying SA-ligand interactions and to highlight the complementarity of experimental and theoretical strategies in elucidating these systems.