The Coagulability of Ammonium Sulfate Precipitated Canine Fibrinogen 1

Abstract

Summary

Fibrinogen, isolated from the plasma of mongrel dogs by fractional ammonium sulfate precipitation, extensively purified and finally dialyzed into 0.01 M sodium citrate was used in a study of coagulability. Coagulability determined by UV absorption at 280 mμ has a value of 93.9 ± 1.2%. Clottability, determined by a comparison of the dry weight of fibrin collected from a fibrinogen solution in which the fibrinogen amount was determined by nitrogen analysis and the conversion factor of 5.92 (16.9% nitrogen in fibrinogen) has a value of 94.7 ± 3.1%. On the basis of total nitrogen from a fibrinogen aliquot and the nitrogen present in the dried fibrin from a similar aliquot the nitrogen coagulability was found to be 96.5 ± 4.3%. The average of the three methods is 95%, showing that approximately 5% of the fibrinogen molecule is lost in the conversion to fibrin. The close agreement between the results of all three methods and the average coagulability of 95% show that the ammonium sulfate precipitation and purification procedures can produce a protein of high purity which is suitable for metabolic studies. The percentage nitrogen of purified fibrin has been found to be 17.3 ± 0.8%.