NEUTRALIZATION OF AUTOPROTHROMBIN C ACTIVITY WITH ANTITHROMBIN

Abstract

A concentrate of antithrombin was made from bovine plasma. When examined with an analytical ultracentrifuge it was found to contain a main component and a small amount of more rapidly sedimentating material. For the main component [Formula: see text] was 4.01 S. The antithrombin concentrate destroyed the activity of purified autoprothrombin C, and most likely antithrombin and antiautoprothrombin C are one and the same substance. The antithrombin preparation was limited in its capacity to destroy autoprothrombin C activity, and equilibrium conditions were reached in 3 to 4 hours. At equilibrium the quantity of autoprothrombin C destroyed was proportional to the antithrombin added to an "excess" of autoprothrombin C. The last traces of the latter activity could only be neutralized with difficulty. Under optimum conditions 1 ml of plasma can neutralize the autoprothrombin C that might generate from 27 ml of plasma. About 0.83 ml of oxalated bovine plasma can neutralize the activity in 1 mg of purified autoprothrombin C.