Adsorption behavior of model proteins on surfaces

To understand the effect of protein shape and size on fast dynamics of proteins adsorption onto hydrophobic surfaces we employ dissipative particle dynamics (DPD), a mesoscale particle-based modeling technique, and study the adsorption behavior of model proteins on hydrophobic surfaces. The model proteins are modeled as semi-flexible rod-like objects consisting of a bundle of linear chains formed by coarse-grained beads that represent lumps of proteins. Three water molecules were combined into a coarse-grained bead and hydrophobic surfaces were represented by dense layers of beads formed in a similar fashion that correspond to small sections of hydrophobic surfaces. We compare systems of large elongated proteins and small elongated proteins that approximately represent proteins over 1000 total residues and peptides of about 200 total residues, respectively, in the presence of a hydrophobic surface. We find distinct differences in the adsorption (and desorption) kinetics of the two types of model proteins. In systems containing small proteins, we observe rapid diffusion and adsorption kinetics as well as frequent desorption events. In systems containing large proteins, protein diffusion is rather slow and once these large proteins adsorb on the hydrophobic surfaces desorption events become rather rare.