Affinity of antithrombin III for insoluble modified polystyrene

In previous papers we described insoluble polystyrenes grafted with L-arginyl methyl ester (PAOM) which exhibit a high affinity for thrombin. Based on their specific interaction with the protease, the resin has been used as stationary phases for affinity chromatographic procedure of thrombin in affinity chromatography (AC) and high performance liquid affinity chromatography (HPLAC). A slight adsorption of antithrombin III (AT III) was shown in AC. In this paper we study the interaction of AT III for PAOM resin in batch procedure. The adsorption is measured using purified protein and corresponds to a monolayer adsorbed on the surface of the polymer. The affinity constant is evaluated kAT = 3.105 1.M-1. Furthermore, insoluble sulfonated polystyrenes grafted with different amino acid were shown to possess an heparin-like behaviour and catalyse the generation of thrombin-AT III complex. So, compared to one of the resin previously mentioned, it could be concluded that PAOM is not heparin-like. When thrombin is adsorbed on the surface of the polymer, AT III cannot interact with the specific seryl residue of the enzyme.