Influence of pH, ionic strength, neutral ions, and thrombin on fibrin polymerization

Abstract

A method for the study of fibrin polymerization as an isolated phenomenon, apart from the over-all reaction of fibrinogen-fibrin conversion by thrombin, is described. Highly purified fibrin monomer, stored at pH 5.3 in 1 m sodium bromide, will polymerize and gel on dilution and pH adjustment. Polymerization rates may be quantitated by serial absorbance determinations at 350 and 600 mµ in a spectrophotometer. The monomer preparation was shown to be free of contaminating fibrinogen or thrombin, and the influence of pH, ionic strength, and neutral ions on its polymerization was studied. The results confirmed the work of previous investigators using less specific methods and indicated that the purified monomer preparation was undenatured. In a recent communication ( Am. J. Physiol. 198: 173, 1960) Landaburu and Seegers reported that thrombin exerted an accelerating or "polymerase" action on polymerization. Polymerization rates determined with the present assay system were found to be uninfluenced by alteration of thrombin concentration and undiminished in its absence.