EFFECT OF SULFATED XYLANS DURING THE INTERACTION OF [I-125] THROMBIN WITH ANTITHROMBIN-III OR HEPARIN-COFACTOR-II OF HUMAN PLASMA

[I-125]-Labeled thrombin was incubated with human plasma and its inter actions with the two plasma protease inhibitors antithrombin III (AT-I II) or heparin cofactor II (HC-LI) were investigated in the presence o f oat spelts xylan sulfate (OSXS), sodium pentosan polysulfate (SP-54) , and the results were compared with heparin and dermatan sulfate. Add ition of OSXS or SP-54 enhanced the complexation of thrombin with HC-I I or with both AT-III and HC-II depending upon the concentration and t he duration of the interactions of the sulfated compounds with plasma. During the 30 s interaction, OSXS and SP-54 enhanced both AT-III-thro mbin and HC-II-thrombin interaction while heparin was more selective a nd enhanced only the AT-III-thrombin interaction. However after a 2 mi n interaction, heparin showed an increase in the HC-II-thrombin intera ction at higher concentrations. The complexations of AT-III-thrombin a nd HC-II-thrombin were reversed in the presence of 200 mu/ml of SP-54 during a 30 s interaction or in presence of 100 mu g/ml of OSXS during a 2 min interaction. The Western blotting method of detecting thrombi n showed that during the 10 s interaction, heparin enhanced the thromb in-AT-III complex formation while OSXS enhanced the thrombin-HC-TI com plex formation.