Molecular mechanism of polyethylene glycol mediated stabilization of protein

Biochem Biophys Res Commun. 2010 Feb 19;392(4):561-6. doi: 10.1016/j.bbrc.2010.01.067. Epub 2010 Jan 25.


The effect of different molar ratios of polyethylene glycol (PEG) on the conformational stability of protein, bovine serum albumin (BSA), was studied. The binding of PEG with BSA was observed by fluorescence spectroscopy by measuring the fluorescence intensity after displacement of PEG with chromophore ANS and had further been confirmed by measuring the intrinsic fluorescence of tryptophan residues of BSA. Co-lyophilization of BSA with PEG at optimum BSA:PEG molar ratio led to the formation of the stable protein particles. Circular dichroism (CD) spectroscopy study suggested that a conformational change had occurred in the protein after PEG interaction and demonstrated the highest stability of protein at the optimum BSA:PEG molar ratio of 1:0.75. Additional differential scanning calorimetry (DSC) study suggested strong binding of PEG to protein leading to thermal stability at optimum molar ratio. Molecular mechanism operating behind the polyethylene glycol (PEG) mediated stabilization of the protein suggested that strong physical adsorption of PEG on the hydrophobic core of the protein (BSA) along with surface adsorption led to the stability of protein.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Circular Dichroism
  • Polyethylene Glycols / chemistry*
  • Protein Binding
  • Protein Conformation
  • Protein Denaturation
  • Protein Stability
  • Serum Albumin, Bovine / chemistry*
  • Spectrometry, Fluorescence
  • Tryptophan / chemistry
  • Urea / chemistry


  • Serum Albumin, Bovine
  • Polyethylene Glycols
  • Tryptophan
  • Urea