How flexible polymers interact with proteins and its relationship with the protein separation method by protein-polymer complex formation.

Bovine serum albumin was selected as a model protein to study the molecular mechanism of interaction between flexible polymer with net negative electrical charge (polyvinylsulphonate and polyacrylic acid) and a non-charged polymer such as poly(ethylene) poly(propylene) oxide (molecular mass 8,400) by using spectroscopies techniques combination: fluorescence emission and circular dichroism. Polyvinylsulphonate and polyacrylic acid interact with the protein due to the coulombic interaction between positive charged protein groups such as amine of lysine and histidine. The poly(ethylene)-poly(propylene) oxide increased the hydrophobic microenvironment around the tryptophan residues. This polymer preserved the secondary and tertiary structure of the protein and did not induce any significant modification in the protein surface area exposed to the solvent.