Mechanism of Action of Vitamin K: Demonstration of a Liver Precursor of Prothrombin

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Science  12 Jan 1973:
Vol. 179, Issue 4069, pp. 192-194
DOI: 10.1126/science.179.4069.192


Extracts of sonicated liver microsomes that are prepared from rats deficient in vitamin K or from rats given vitamin K antagonists contain a factor that liberates a thrombin-like activity when it is incubated with venom from Echis carinatus. The amount of this factor is low in control rats and in hypoprothrombinemic rats given vitamin K 1 hour before they were killed. These data indicate that this factor is a protein precursor of prothrombin, which is synthesized in the liver.