COMPUTER-SIMULATION MODEL OF THE ADSORPTION OF PROTEIN POLYSACCHARIDE COMPLEXES

Monte Carlo computer simulation on a two-dimensional square lattice has been used to study the adsorption of hybrid molecules (protein-polysaccharide complexes) at a hard wall. Compact macromolecules (globular proteins) are modelled as soft particles made from connected subunits. The average conformation of the soft particles is controlled by a deformability parameter that is coupled to the particle perimeter length. The soft particles are irreversibly bound to highly disordered polymers (polysaccharides) modelled as so-called 'fractal polymers'. The resulting hybrid molecule has features in common with covalent Maillard products formed by dry heating of globular proteins with dextrans. Numerical results are presented which show the effect of linkage of the non-adsorbing fractal polymer on the adsorption of the soft particle subunits. We investigate the dependence of the surface coverage on the number of bound fractal polymers per hybrid molecule and on the size of the fractal polymer chains. The relevance of the simulation to recent experimental results on the emulsion stabilizing properties of protein-dextran hybrid molecules is discussed.