Immunochemical Determination of Human Prothrombin

Abstract

An antiserum was prepared by immunising guinea pigs with a purified human prothrombin preparation. The antiserum inhibited the prothrombin-proconvertin activity of plasma. The plasma component reacting with the antiserum could not be demonstrated in serum. On gel electrophoresis, gel filtration, and adsorption with barium sulphate the immunological plasma component behaved exactly like prothrombin.

The concentration of prothrombin in normal citrated plasma relative to that in a normal plasma pool was determined with an immunochemical method. The variation coefficient was found to be 14%. The mean concentration was estimated at 6 to 10 mg/100 ml. The electrophoretic mobility of prothrombin varied with the presence and absence of calcium ions in the buffer, a variation indicating that calcium ions are bound to prothrombin.

Key Words:

• Blood coagulation
• α-globulins
• prothrombin