Molecular interactions of acebutolol hydrochloride to human serum albumin: A combined calorimetric, spectroscopic and molecular modelling approach

Abstract

Acebutolol hydrochloride (AH), a beta blocker is generally used in the cure of cardiovascular disorders. We have examined the interaction between AH and human serum albumin (HSA) employing UV–vis, fluorescence quenching, circular dichroism (CD), isothermal titration calorimetry and molecular docking methods. Tryptophan fluorescence intensity of HSA was strongly quenched by AH and the binding constants (K b ) were determined by fluorescence quenching indicating high affinity of AH for HSA. The negative ΔG° value for binding indicated that HSA-AH interaction was a spontaneous process. Existence of hydrophobic interactions, and hydrogen bonds were indicated from the calorimetric analysis, thus facilitating the binding of AH with HSA. Secondary structure changes were confirmed from far-UV CD studies. Further, molecular docking studies revealed AH binds with HSA, in the binding site located in Sudlow Site I of subdomain IIA of HSA. This work provides a useful experimental strategy for investigating the interactions of beta blocker AH with HSA, thus helping the activity and drug binding mechanism.