Heparin cofactor II (HCII) was purified from plasma to homogeneity. The procedure
includes adsorption with (Al)OH3, fractionation with polyethylene glycol 6000, chromatography
on QAE-Sephadex A-50, on heparin-Sepharose 4B and on Sephadex G-150. QAE-Sephadex
A-50 chromatography provides a good separation of HCII from antithrombin III (AT)
and most contaminants having a heparin affinity similar to that of HCII. HCII is eluted
at 0.28 M NaCl from the heparin-Sepharose column. After gel filtration on G-150, contaminating
AT was removed by immunoadsorption. Purified HCII shows an apparent Mr of 66,500 dal tons as analyzed on SDS-polyacrylamide gel and 62,100 daltons by ultracentrifugation.
Antibodies to HCII were raised in rabbits. Former antisera mostly directed to a contaminating
protein were used to remove it from the HCII preparation. Antibodies to HCII were
made monospecific by immunoadsorption on HCII-free plasma linked to Sepharose 4B.
Since many functional AT assays have neglected the presence of HCII in plasma, antibodies
to HCII using as immunoadsorbent will provide a more specific test for AT.
Key words
Heparin cofactors - Antibody specificity - Antithrombin III - Unknown protein - Fluid
dynamics