See also Protease Inhibitors in General

Protease inhibitors include alpha-1 antitrypsin and the antithrombins such as antithrombin III which prvent the effects of thrombin. Another proteinase inhibitor is C1-esterase inhibitor which reduces or eliminates the activity of C1-esterase, which is the activated first component of complement, C1.

Purification of Protease Inhibitors from Plasma

Antithrombin-III (AT-III) has been prepared from plasma or Cohn Fraction IV-1 in a 5 step method consisting of (a0 partial purificaiton by precipitating unwanted proteins using PEG, (b) solution of AT-III from the PEG supernatant by batch adsorption and elution on heparin-sepharose (c) concentrating and deslating the eluted AT-III by ultrafiltration (d) pastuerization of AT-III by heating the concentrate for 10 hours and (e) sterile filtration. 

Shearer (US4656254) disclose a method of separating antitrhombin III from an aqueous solution of palsma proteins by (a) adjusting a buffer solution and the aqueous solution to pH 9.0 – 11 and contacting the solution with a water insoluble, cross linked sulfated polysaccharide gel matrix to adorb antithrombin-III, and (b) eluting the antithrombin IIII.