Conformational transitions provoked by organic solvents in chicken egg ovalbumin: mimicking the local environment

Protein J. 2013 Jan;32(1):7-14. doi: 10.1007/s10930-012-9453-2.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chickens
  • Circular Dichroism
  • Ethylene Glycol / pharmacology
  • Glyoxal / pharmacology
  • Ovalbumin / chemistry*
  • Polyethylene Glycols / pharmacology
  • Protein Structure, Secondary / drug effects
  • Solvents / pharmacology
  • Spectroscopy, Fourier Transform Infrared

Substances

  • Solvents
  • Polyethylene Glycols
  • Glyoxal
  • Ovalbumin
  • Ethylene Glycol