Spectroscopic study of interaction between osthole and human serum albumin: Identification of possible binding site of the compound

• Published in: Journal of luminescence Vol. 143; pp. 328 - 336
• Main Authors: Bijari, Nooshin, Shokoohinia, Yalda, Ashrafi-Kooshk, Mohammad Reza, Ranjbar, Samira, Parvaneh, Shahram, Moieni-Arya, Maryam, Khodarahmi, Reza
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2013; Elsevier
• Subjects: Analytical, structural and metabolic biochemistry; Binding; Binding sites; Biological and medical sciences; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fluorescence; Fluorescence quenching; Fluorescence resonance energy transfer; Fundamental and applied biological sciences. Psychology; Human; Human serum albumin; Materials science; Mathematical analysis; Miscellaneous; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Osthole; Photoluminescence; Physics; Protein surface hydrophobicity; Proteins; Serum albumin; Spectroscopy; Treatment of materials and its effects on microstructure and properties; CD; Human serum albumin; PSH; ANS; Protein surface hydrophobicity; HSA; FRET; Fluorescence resonance energy transfer; Osthole; Fluorescence quenching; Cadmium; Fluorescence; Tryptophan; Excitation energy transfer; Radioactive tracers; Quenching; Proteins; Albumins; Fluorophore; Calcium nitride; Luminescence quenching; Displacement measurement; Energy transfer; Monitoring
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/j.jlumin.2013.04.045

The studies on the interaction between human serum albumin (HSA) and drugs have been an interesting research field in life science, chemistry and clinical medicine. Osthole possesses a variety of pharmacological activities including anti-tumor, anti-inflammation, anti-seizure, anti-hyperlipidemic and anti-osteoporosis effects. The interaction of osthole with HSA and its binding site in HSA by spectroscopic methods is the subject of this work. By monitoring the intrinsic fluorescence of the single Trp214 residue and performing site markers displacement measurements, the specific binding of osthole in the vicinity of Sudlow's site I of HSA has been clarified. The changes in the secondary structure of HSA after its complexation with ligand were studied with CD spectroscopy, which indicate that osthole induced only a slight decrease in the helix structural content of the protein. In addition, the mean distance between osthole and HSA fluorophores is estimated to be 4.96nm using Föster's equation on the basis of the fluorescence energy transfer. Furthermore, the synchronous fluorescence spectra show that the microenvironment of the tryptophan residues does not have obvious changes. Osthole can quench the intrinsic fluorescence of HSA by dynamic quenching, and analysis of the thermodynamic parameters of binding showed that hydrophobic interactions play an important role in the stabilizing of the complex. Increase of protein surface hydrophobicity (PSH) was also observed upon the osthole binding. •Hydrophobic interactions play an important role in osthole–HSA interaction.•Sudlow's I site is possible binding site of osthole.•Osthole inhibits esterase activity of HSA.•Osthole binding induces no gross protein structural changes.