Pawar SK, Jaldappagari S. Interaction of repaglinide with bovine serum albumin: Spectroscopic and molecular docking approaches.
J Pharm Anal 2019;
9:274-283. [PMID:
31452966 PMCID:
PMC6702422 DOI:
10.1016/j.jpha.2019.03.007]
[Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 01/28/2023] Open
Abstract
Repaglinide (RPG) regulates the amount of glucose by stimulating the pancreas to release insulin in the blood. In view of its biological importance, we have examined the interaction between RPG and a model protein, bovine serum albumin (BSA) employing various spectroscopic, electrochemical and molecular docking methods. Fluorescence spectra of BSA were recorded in the presence and absence of RPG in phosphate buffer of pH 7.4. Fluorescence intensity of BSA was decreased upon the addition of increased concentrations of RPG, indicating the interaction between RPG and BSA. Stern-Volmer quenching analysis results revealed that RPG quenched the intensity of BSA through dynamic quenching mechanism. This was further confirmed from the time-resolved fluorescence measurements. The binding constant as calculated from the spectroscopic and voltammetric results was observed to be in the order of 104 M−1 at 298 K, suggesting the moderate binding affinity between RPG and BSA. Competitive experimental results revealed that the primary binding site for RPG on BSA was site II. Absorption and circular dichroism studies indicated the changes in the secondary structure of BSA upon its interaction with RPG. Molecular simulation studies pointed out that RPG was bound to BSA in the hydrophobic pocket of site II.
Dynamic mode of quenching mechanism was noticed in RPG-BSA interaction.
RPG was bound to BSA at the Sudlow’s site II and the resultant RPG-BSA complex was mainly stabilized by hydrophobic forces.
The binding constant of RPG-BSA of the order of 104 M−1 at 298 K indicated the non-covalent interactions.
Secondary structural changes in BSA upon binding to RPG were evident from absorption and circular dichroism studies.
The influence of β-cyclodextrin and metal ions on RPG-BSA binding affinity was examined.
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