Selective Inactivation of Fibrin Stabilizing Factor Contaminant in Fibrinogen

Abstract

THE fibrin stabilizing factor (FSF) is a thermolabile plasma protein which in the presence of calcium converts a loosely cross-linked, urea-soluble fibrin clot (fibrin s) into a urea-insoluble gel (fibrin i)^1,2. FSF reacts sto-chiometrically with fibrinogen in the latter's conversion to fibrin³ and requires the presence of free sulphydryl groups for its activity⁴. The recently established enzymatic nature of this factor has led to the suggestion that it be renamed ‘fibrinase’⁵. Differences in the activity of plasma FSF have been found to be associated with a variety of clinical conditions⁶. More recently, the occurrence of congenital deficiencies of FSF has been reported and shown to be responsible for abnormal hæmostasis and poor wound healing^7,8. In this connexion, it is of interest that fibrin s clots do not support the growth of fibroblast cultures nearly so well as normal plasma clots⁹, a phenomenon which may in part, at least, be due to the fact that they are less resistant to lysis by plasmin¹⁰.