title: pH-dependent differential interacting mechanisms of sodium dodecyl sulfate with bovine serum fetuin: a biophysical insight.
abstract: Sodium dodecyl sulfate (SDS)-glycoprotein interaction serves as a model for a biological membrane. To get mechanistic insight into the interaction of SDS and glycoprotein, the effect of SDS on bovine serum fetuin (BSF) was studied in subcritical micellar concentrations at pH 7.4 and pH 2 using multiple approaches. SDS interacts electrostatically with BSF through its negatively charged head groups at pH 2 and hydrophobically via its alkyl chains at pH 7.4 up to a 1:20 molar ratio of BSF to SDS. However, at higher concentrations of SDS, BSF undergoes amyloid fibril formation at pH 2, as confirmed by enhanced ThT fluorescence, β-sheet formation, and TEM microscopy, whereas BSF undergoes induction of an α-helical structure in the presence of higher SDS concentration at pH 7.4. The increase in α-helical content with increasing SDS concentrations constrains the environment around tryptophan. As a consequence, the interconversion of tryptophan conformers decreases, resulting in a decrement of the fluorescence lifetime for BSF in the presence of SDS at pH 7.4.
authors.affiliation: Interdisciplinary Biotechnology Unit, Aligarh Muslim University , Aligarh 202002, India.
authors.forename: Nida
authors.initials: N
authors.lastname: Zaidi
authors.forename: Saima
authors.initials: S
authors.lastname: Nusrat
authors.forename: Fatima Kamal
authors.initials: FK
authors.lastname: Zaidi
authors.forename: Rizwan H
authors.initials: RH
authors.lastname: Khan
mesh_terms: D000818:Animals; D052160:Benzothiazoles; D002151:Calorimetry; D002417:Cattle; D002942:Circular Dichroism; D060748:Fetuins / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D046529:Microscopy, Electron, Transmission; D009391:Nephelometry and Turbidimetry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D013816:Thermodynamics; D013844:Thiazoles / Q000737:chemistry / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry
chemical_list: D052160:Benzothiazoles; D060748:Fetuins; D013844:Thiazoles; C009462:thioflavin T; D012967:Sodium Dodecyl Sulfate; D014364:Tryptophan