A theory of protein-resin interaction in hydrophobic interaction chromatography

Docking simulations were performed in order to investigate surface area of interaction between several ribonucleases and a reduced model for the hydrophobic moiety used in Phenyl Sepharose using the program AutoDock 3.0. For each ribonucelase, 80 independent simulations with populations consisting of 100 random structures were performed and from these the most probable docked protein-ligand conformations were obtained. A new methodology was used to select the most probable conformations, based on qualitative and quantitative considerations. The interacting amino acids in each protein were identified. The average surface hydrophobicity of the interfacial zone (local hydrophobicity, LH) was determined. The LH showed a high correlation level (r2 = 0.99) with the "hydrophobic contact area" (HCA) experimentally determined for the different ribonucleases as well as with the dimensionless retention time (r2 = 0.90). This study allowed us to identify the zones on the protein surface most probably involved in protein retention in HIC, without tedious experimental work. Given the good correlation level obtained, this new methodology may constitute a novel approach that could be used to predict protein behavior in HIC.