Effects of different ions on the interactions of heparin with bovine antithrombin III and thrombin.

Of four Tris-salts tested (chloride, sulfate, phosphate and acetate), chloride caused complete elution of antithrombin III (AT III) from a heparin-Sepharose column and sulfate caused partial elution. AT III was also partially eluted from the column with sodium acetate, but not Tris acetate. On the other hand, thrombin was eluted from the column with the Tris-salts in the order chloride greater than sulfate greater than acetate, but was not eluted with Tris-phosphate. Thrombin was also eluted from the column with sodium acetate. These findings indicate that the affinity of heparin to AT III was influenced only by strongly electronegative ions, whereas its affinity to thrombin was affected by both strongly electropositive and strongly electronegative ions.