New insight into the stereoselective interactions of quinine and quinidine,with bovine serum albumin |
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Authors: | Yan Liu Mingmao Chen Shuaihua Wang Jingjing Lin Lizhen Cai Ling Song |
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Affiliation: | 1. The State Key Lab of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, China;2. Institute of Biomedical and Pharmaceutical Technology, Fuzhou University, Fuzhou, Fujian, China |
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Abstract: | Quinine (QN) and quinidine (QD), the chief quinoline alkaloids of various species of cinchona bark, are stereoisomers to each other. In this study, a series of appropriate and efficient methods have been applied to compare the binding modes of QN and QD with bovine serum albumin (BSA). The isothermal titration calorimetry and room temperature phosphorescence results show that both QN and QD can interact with BSA at one binding site to form drug–protein complexes, mainly through enthalpic driving force with the binding affinity order: QN > QD. The fluorescence resonance energy transfer and time‐resolved fluorescence spectroscopy exhibits that QN has a larger energy transfer and more intensified binding capacity for BSA than QD. Data of dynamic light scattering reveal that the aggregate state of BSA is changed during this binding process, and the particle size distribution of QN‐BSA bioconjugate is larger than that of QD. Nuclear magnetic resonance analysis indicates that aromatic protons make more contribution during ligand‐protein complexation than that of aliphatic protons. The circular dichroism spectra exhibit different degrees of changes in BSA secondary structures in the presence of QN and QD, respectively. Copyright © 2014 John Wiley & Sons, Ltd. |
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Keywords: | Cinchona alkaloid stereoisomers Bovine serum albumin Stereoselectivity Binding capacity Isothermal titration calorimetry Spectroscopic methods |
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