Interaction between polystyrene sulfonic acid

The basis of the separation of amino acids by AAA lies in the interaction between acids - present in the elution buffer - and the stationary phase. This resin is made up of small sulfonated polystyrene particles. The negative charge of the sulfonic acid residues is counterbalanced by the Li+ -cations of the elution buffer. As the whole separation process takes place at a weakly acidic pH, the carboxylic acid residues are protonated and the interaction with the stationary phase of the column is achieved by the protonated (and thus positively charged) amino group(s) of the amino acids. The more basic the amino acid is, the stronger the interaction with the stationary phase and - consequently - the longer the retention time. So it is easily understood... 

We now report results concerning the interactions between these two proteins and two of these polystyrene derivatives sulfonated polystyrene (PSSO3) and sulfonate-glutamic acid sulfonamide polystyrene (PSSO2GIU). The adsorption of each protein was studied either in purified system or in plasma and the binding constants were determined. Moreover, the catalysed formation of thrombin-anti-thrombin III complex was examined and compared with the antithrombic activity measured through thrombin clotting times of plasma preincubated with these polymers. 

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