Abstract
It is known that heparin does not prevent the coagulation of a fibrinogen solution by purified thrombin. 1 It likewise is unable to prevent the conversion of isolated prothrombin to thrombin. 2 , 3 To exert its powerful anticoagulant action, heparin requires an additional factor which is known to be present in blood, plasma, and serum. 1 , 4 , 5 This factor has been shown by Quick 4 to be contained in the serum albumin fraction.
We have investigated the activity of various components of the albumin fraction in producing the anticoagulant effect of heparin on the fibrinogen-thrombin system.
The thrombin was obtained by the method of Eagle, 6 and the fibrinogen was prepared in the usual manner by repeated precipitations with sodium chloride. Heparin was used in the form of the pure sodium salt.†
The activities of the albumin components studied are shown in Table I, which reproduces a typical experiment. The letters in the first column of this table stand for the following compounds: A, crystalline albumin from human serum, prepared by Dr. F. E. Kendall of the Research Division for Chronic Diseases, Welfare Island. We are greatly indebted to Dr. Kendall for different specimens of this substance. B, albumin from sheep plasma, prepared according to Howe. 7 C, fraction from human plasma insoluble at 55% saturation with ammonium sulfate, presumably containing the globoglycoid of Hewitt. 8 D, fraction from human plasma insoluble at 75% saturation with ammonium sulfate. E, fraction from human plasma insoluble at 100% saturation with ammonium sulfate. This fraction presumably contained the seroglycoid of Hewitt. 9 F, the supernatant solution after removal of E, dialyzed and concentrated by ultrafiltration.
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