Spectroscopic Investigation on the Interaction of Pyrimidine Derivative, 2-Amino-6-hydroxy-4-(3,4-dimethoxyphenyl)-pyrimidine-5-carbonitrile with Human Serum Albumin: Mechanistic and Conformational Study

Industrial & Engineering Chemistry Research (Impact Factor: 2.59). 12/2012; 51(1):95–102. DOI: 10.1021/ie202005c


In the present study, fluorescence spectroscopy in combination with UV–vis absorption spectroscopy and synchronous fluorescence spectroscopy (SFS) was employed to investigate the binding affinity of pyrimidine derivative, 2-amino-6-hydroxy-4-(3,4-dimethoxyphenyl)-pyrimidine-5-carbonitrile (AHDMPPC) to human serum albumin (HSA) under the physiological conditions. In the mechanism discussion, it was proved that the fluorescence quenching of HSA by AHDMPPC is a result of the formation of AHDMPPC–HSA complex. The quenching mechanism and number of binding sites (n ≈ 1) were obtained by fluorescence titration data. Binding parameters calculated from Stern–Volmer method showed that the AHDMPPC bind to HSA with the binding affinities of the order 104 L mol–1. The thermodynamic parameters studies revealed that the binding was characterized by negative enthalpy and positive entropy changes −13.06 kJ/mol and 51.34 J/mol K–1 (from the Van’t Hoff equation) and suggest that the binding reaction was exothermic and hydrophobic interaction is the predominant intermolecular forces stabilizing the complex. The specific binding distance (r = 2.25 nm) between donor HSA and acceptor AHDMPPC was obtained according to fluorescence resonance energy transfer (FRET). Furthermore, the synchronous spectral result, three–dimensional fluorescence spectra and circular dichroism (CD) indicates that the secondary structure of HSA was changed in the presence of AHDMPPC.

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    • "The content of proteins in body fluid can be used as a vital index for the clinical diagnosis and health evaluation; therefore, the direct determination of protein is significant in life sciences, clinical medicine and chemical investigation. The interaction between bio-macromolecules and drugs has attracted great interest for several decades [1] [2] [3] and much research has been focused on two central questions about proteins: what are the determinant factors that influence on the protein structures and functions, and how does a factor affect their biological activity [4] [5]. Serum albumin (SA), the main protein in the blood plasma acting as the transporter and disposition of many drugs, has been frequently used as a model protein for investigating the protein folding and ligand-binding mechanism. "
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    ABSTRACT: A biologically active antibacterial reagent, 2–amino-6-hydroxy–4–(4- N, N-dimethylaminophenyl)-pyrimidine-5-carbonitrile (AHDMAPPC) was synthesized. It is employed to investigate the binding interaction with the Bovine Serum Albumin (BSA) in detail using different spectroscopic methods. It exhibits antibacterial activity against Escherichia coli and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites (n≈1) were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change (ΔH), free energy (ΔG) and entropy change (ΔS) for the reaction were calculated to be 15.15 kJ/mol, –36.11 kJ/mol and 51.26 J/mol K according to van't Hoff equation respectively. The results indicated that the reaction was an endothermic, spontaneous process and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Förster's theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV-visible, synchronous fluorescence, circular dichroism (CD) and three-dimensional fluorescence spectra. All these results indicated that AHDMAPPC could bind to BSA and be effectively transported and eliminated in the body. It could be a useful guideline for further drug design.
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    ABSTRACT: The interaction of ceftriaxone sodium (CS), a cephalosporin antibiotic, with the major transport protein, bovine serum albumin (BSA), was investigated using different spectroscopic techniques such as fluorescence, circular dichroism (CD), and UV-vis spectroscopy. Values of binding parameters for BSA-CS interaction in terms of binding constant and number of binding sides were found to be 9.00 × 10(3) , 3.24 × 10(3) , and 2.30 × 10(3) M(-1) at 281, 301, and 321 K, respectively. Thermodynamic analysis of the binding data obtained at different temperatures showed that the binding process was spontaneous and was primarily mediated by van der Waals force or hydrogen bonding. CS binding to BSA caused secondary structural alterations in the protein as revealed by CD results. The distance between CS and Trp of BSA was determined as 3.23 nm according to the Förster resonance energy transfer theory.
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