Zinc binding to fibrinogen and fibrin

Zinc binding to fibrinogen and fibrin was studied by two techniques. Scatchard analysis of ultrafiltration eluates reveals that fibrinogen has multiple Zn(II)-binding sites, KD (fibrinogen) = 18 microM; n = 6. The zinc content of the "collapsed" fibrin gel supernatant was also determined by atomic absorption spectroscopy and analyzed by a Scatchard plot (KD (fibrin) = 8 microM, n = 6). In other experiments, Zn(II) did not displace 45Ca(II) from fibrin. It appears that the binding of zinc to fibrinogen or fibrin is distinct from that of calcium, and that the zinc-binding characteristics of fibrinogen and fibrin are not significantly affected by the transformation of one into the other.