PARTICIPATION OF SIALIC-ACID RESIDUE IN THE FIBRINOGEN-FIBRIN CONVERSION BY THROMBIN

In order to estimate the effects of sialic acid residues in fibrinogen on the fibrinogen-fibrin conversion by bovine thrombin the Michaelis constant (K-m) and maximum velosity (V-max) were determined. The K-m value obtained by the use of intact-fibrinogen was smaller than that of asialo-fibrinogen. This fact suggests that the sialic acid residues affected the formation of the enzyme-substrate complex. It was also found that in comparison with the asialo-fibrinogen, the intact-fibrinogen was significantly influenced in the gel formation time by the ionic strength in the reaction solution.