title: Urea-induced binding between diclofenac sodium and bovine serum albumin: a spectroscopic insight.
abstract: We investigated the interaction of diclofenac sodium (Dic.Na) with bovine serum albumin (BSA) in the absence and presence of urea using different spectroscopic techniques. A fluorescence quenching study revealed that the Stern-Volmer quenching constant decreases in the presence of urea, decreasing further at higher urea concentrations. The binding constant and number of binding sites were also evaluated for the BSA-Dic.Na interaction system in the absence and presence of urea using a modified Stern-Volmer equation. The binding constant is greater at high urea concentrations, as shown by the fluorescence results. In addition, for the BSA-Dic.Na interaction system, a static quenching mechanism was observed, which was further confirmed using time-resolved fluorescence spectroscopy. UV-vis spectroscopy provided information about the formation of a complex between BSA and Dic.Na. Circular dichroism was carried out to explain the conformational changes in BSA induced by Dic.Na in the absence and presence of urea. The presence of urea reduced the α-helical content of BSA as the Dic.Na concentration varied. The distance r between the donor (BSA) and acceptor (Dic.Na) was also obtained in the absence and presence of urea, using fluorescence resonance energy transfer. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.
authors.forename: Neeraj
authors.initials: N
authors.lastname: Dohare
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.
authors.forename: Abbul Bashar
authors.initials: AB
authors.lastname: Khan
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.
authors.forename: Fareeda
authors.initials: F
authors.lastname: Athar
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.
authors.forename: Sonu Chand
authors.initials: SC
authors.lastname: Thakur
authors.affiliation: Biophysical Chemistry Laboratory, Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi, India.
authors.forename: Rajan
authors.initials: R
authors.lastname: Patel
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004008:Diclofenac / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014508:Urea / Q000737:chemistry*
chemical_list: D004008:Diclofenac; D012710:Serum Albumin, Bovine; D014508:Urea
keywords: FRET; bovine serum albumin; diclofenac sodium; quenching