Chromatography of rhAT and phAT on a TSK-Gel Heparin-5PW affinity column. Sample load was 175 μg (A) and 25 μg (B). AT was eluted with a 0- to 3-mol/L NaCl gradient in equilibration buffer with detection at 215 nm. For (A), the dotted line represents phAT and the solid line represents rhAT. For (B), the solid line represents rhAT protein and the circles represent thrombin inhibition activity. The difference in retention times between panels resulted from a 10-minute wash preceding the elution gradient in (A) that was not used in (B).