HEPARIN-LIKE ACTIVITY OF INSOLUBLE SULFONATED POLYSTYRENE RESINS .2. PROPERTIES OF POLYAMPHOLYTES

By introducing variable amounts of amino groups and sulfonate groups on the same chains of polystyrene resins (Polyampholytes equals PA), the effects of the net charge borne by the PA resins on the binding of hydrogen ions, heparin-like properties and the adsorption of thrombin were studied. It was demonstrated that the apparent acidity constant of the amino groups was strongly dependent upon the electrical environment of these groups: they behaved like strong bases when surrounded by negative charges and like weak bases when surrounded by positive charges. The adsorption of active thrombin was strongly involved in the heparin-like properties of the hydrophilic resins bearing a net negative charge. In the presence of the hydrophilic resins bearing a net positive charge, no adsorption of active thrombin was detected. The gross effect of one positively charged amino group was to neutralize the heparin-like activity of one sulfonate group.