title: Study of the interaction between 8-azaguanine and bovine serum albumin using optical spectroscopy and molecular modeling methods.
abstract: The interaction between 8-azaguanine (8-Azan) and bovine serum albumin (BSA) in Tris-HCl buffer solutions at pH 7.4 was investigated by means of fluorescence and ultraviolet-visible (UV-Vis) spectroscopy. At 298 K and 310 K, at a wavelength of excitation (λ (ex)) of 282 nm, the fluorescence intensity decreased significantly with increasing concentrations of 8-Azan. Fluorescence static quenching was observed for BSA, which was attributed to the formation of a complex between 8-Azan and BSA during the binding reaction. This was illuminated further by the UV-Vis absorption spectra and the decomposition of the fluorescence spectra. The thermodynamic parameters ∆G, ∆H, ∆S were calculated. The results showed that the forces acting between 8-Azan and BSA were typical hydrophobic forces, and that the interaction process was spontaneous. The interaction distance r between 8-Azan and BSA, evaluated according to fluorescence resonance energy transfer theory, suggested that there is a high possibility of energy transfer from BSA to 8-Azan. Theoretical investigations based on homology modeling and molecular docking suggested that binding between 8-Azan and BSA is dominated by hydrophilic forces and hydrogen bonding. The theoretical investigations provided a good structural basis to explain the phenomenon of fluorescence quenching between 8-Azan and BSA.
authors.affiliation: College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
authors.forename: Qiao-Ling
authors.initials: QL
authors.lastname: Gong
authors.forename: Xin-Gen
authors.initials: XG
authors.lastname: Hu
authors.forename: Guo-Yong
authors.initials: GY
authors.lastname: Fang
authors.forename: Xin-Hua
authors.initials: XH
authors.lastname: Li
mesh_terms: D000818:Animals; D001375:Azaguanine / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D002417:Cattle; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods; D013057:Spectrum Analysis / Q000379:methods; D013816:Thermodynamics
chemical_list: D012710:Serum Albumin, Bovine; D001375:Azaguanine