HAMSTER ANTITHROMBIN .3. PURIFICATION, CHARACTERIZATION AND ACUTE-PHASE RESPONSE

Antithrombin III was purified to homogeneity from hamster plasma by af finity chromatography on heparin-agrose, ion-exchange chromatography o n Mono Q and size-exclusion chromatography on TSK G3000SWG column with 50% yield. The molecular mass of hamster antithrombin III was estimat ed at 62.5 kDa and the absorption coefficient (A(280 nm)(1%, 1cm)) at 6.48 (in 0.1 M sodium phosphate pH 7.0). Several isoforms of the inhib itor were detected with the pI in range of 4.95-5.25. The protein cont ains all residues characteristic for complex-type carbohydrate chains. The N-terminal amino acid sequence shows 84% of identity to mouse and 76% to human analogue. The hamster antithrombin III gives low immunol ogical cross-reactivity with antibodies to human antithrombin III. Ini tiation of the acute phase response only slightly affected the plasma concentration of inhibitor (+/-10% within 72-h period). The kinetic da ta suggest high efficiency in bovine and human thrombin inhibition. In summary, the study shows only similarities between hamster and other mammal antithrombins.