Investigation of the behavior of HSA upon binding to amlodipine and propranolol: Spectroscopic and molecular modeling approaches

The interaction between human serum albumin (HSA) and two drugs – amlodipine and propranolol – was investigated using fluorescence, UV absorption and circular dichroism (CD) spectroscopy. In addition, the binding site was established by applying molecular modeling technique. Fluorescence data suggest that amlodipine will quench the intrinsic fluorescence of HSA; whereas propranolol enhances the fluorescence of HSA. The binding constants for the interaction of amlodipine and propranolol with HSA were found to be 3.63 × 105 M−1 and 2.29 × 104 M−1, respectively. The percentage of secondary structure feature of each one of the HSA-bound drugs, i.e. the α-helix content, was estimated empirically by circular dichroism. The results indicated that amlodipine causes an increase, and that propranolol leads to a decrease in α-helix content of HSA. The spectroscopic analysis indicates that the binding mechanisms of the two drugs are different from each other. The data obtained by the molecular modeling study indicated that these drugs bind, with different affinity, to different sites located in subdomain IIA and IIIA.

The interaction between human serum albumin (HSA) and the two drugs – amlodipine and propranolol – was investigated by different methods. The results indicated that amlodipine give rise an increase, while propranolol leads to a decrease in α-helix content of HSA. Data obtained by molecular modeling study suggested that these drugs bind in different sites in subdomain IIA and IIIA with different affinity.Figure optionsDownload as PowerPoint slideHighlights
► The interaction of HSA with two drugs – amlodipine and propranolol – was investigated. The binding constants of amlodipine and propranolol with HSA were estimated. Amlodipine induces an increase and propranolol a decrease of α-helices content of HSA. These drugs bind in different sites in subdomain IIA and IIIA with different affinity.