[Analysis of the fragment D-fibrin monomer complex formation by salting-out fractionation].

The fragment D-fibrin monomer complex formation was studied by ammonium sulfate fractionation of the reaction mixtures initially consisting of 0.15-4.00 mg/ml of fragment D and 1.00 mg/ml of fibrin monomer, It was shown that in these mixtures the equilibrium was reached in not more than 15 sec. Fragment D binding to fibrin dependent on the fragment concentration. The Scatchard analysis of this dependence revealed a maximum of fragment D binding to one fibrin molecule of 2.95 +/- 0.28 with a Ka value of (9.04 +/- 1.08) x 10(-5) M-1 (n = 6), thus indicating a strong fragment--fibrin affinity.