Surface Properties of Protein-Polyelectrolyte Solutions. Impact of Polyelectrolyte Hydrophobicity

The strong influence of an amphiphilic polyelectrolyte,poly(N,N-diallyl-N-hexyl-N-methylammonium chloride), on the surfaceproperties ofsolutions of globular proteins (lysozyme, beta-lactoglobulin, bovineserum albumin, and green fluorescent protein) depends on the proteinstructure and allows elucidation of the contribution of hydrophobicinteractions in the protein-polyelectrolyte complex formationat the liquid-gas interface. At the beginning of adsorption,the surface properties are determined by the unbound amphiphilic component,but the influence of the protein-polyelectrolyte complexesof high surface activity increases at the approach to equilibrium.The kinetic dependencies of the dilational dynamic surface elasticitywith one or two local maxima give a possibility to distinguish clearlybetween different steps of the adsorption process and to trace theformation of the distal region of the adsorption layer. The conclusionsfrom the surface rheological data are corroborated by ellipsometricand tensiometric results.

Automated summary

The influence of an amphiphilic polyelectrolyte on the surface properties of protein solutions depends on the protein structure and can help understand the contribution of hydrophobic interactions in protein-polyelectrolyte complex formation. The adsorption process can be monitored through dilational dynamic surface elasticity measurements, and the conclusions are supported by ellipsometric and tensiometric results.