title: Conformational transitions provoked by organic solvents in chicken egg ovalbumin: mimicking the local environment.
abstract: Glycoprotein ovalbumin is an important protein to study helix/sheet transitions as it possess almost equal amount of α-helix and β-sheet. Conformational changes on ovalbumin at various concentrations of glyoxal, ethylene glycol (EG) and polyethylene glycol-400 (PEG-400) were investigated by fluorescence spectroscopy, circular dichroism, attenuated total reflection Fourier transform infra red spectroscopy, 8-anilino-1-naphthalenesulfonic acid and thioflavin T assay. A partially folded state of ovalbumin at 50 % v/v glyoxal was detected that preceded the onset of the aggregation process at the maximum concentration (90 % v/v) of this aldehyde. Aggregates of ovalbumin in the presence EG and PEG-400 were deduced at 70 and 80 % v/v respectively. Maximum aggregation of ovalbumin was observed at 80 % v/v PEG-400, followed by 70 % v/v EG and 90 % v/v glyoxal. Our study confirms that protein aggregation is influenced by the chemistry of organic solvent used thus follows an order of solvent effectiveness (PEG > EG > glyoxal) in inducing the transition. These results provide valuable information on the mechanisms involved in the pathogenesis of some conformational diseases. The α-helix to β-sheet conversion is a diagnostic feature of protein aggregation and has been considered as a general characteristic of amyloid fibrillogenesis in vitro.
authors.affiliation: Department of Biochemistry, Faculty of Life Science, Aligarh Muslim University, Aligarh, 202 002, India. afshiniram@gmail.com
authors.forename: Afshin
authors.initials: A
authors.lastname: Iram
authors.forename: Aabgeena
authors.initials: A
authors.lastname: Naeem
mesh_terms: D000818:Animals; D002645:Chickens; D002942:Circular Dichroism; D019855:Ethylene Glycol / Q000494:pharmacology; D006037:Glyoxal / Q000494:pharmacology; D010047:Ovalbumin / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000494:pharmacology; D017433:Protein Structure, Secondary / Q000187:drug effects; D012997:Solvents / Q000494:pharmacology; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D012997:Solvents; D011092:Polyethylene Glycols; D006037:Glyoxal; D010047:Ovalbumin; D019855:Ethylene Glycol