Copper-chelatin: isolation from various eucaryotic sources.

Bovine factor V was treated with highly purified neuraminidase to yield asialo factor V. Different preparations of factor V were found to exhibit heterogeneity with respect to the content of sialic acid, which ranged from 5% to 12%. The activity of asialo factor V in accelerating blood coagulation was found to be significantly greater than native factor V; thus, sialic acid is not essential for activity but may modulate its function. Asialo-factor V was 3.8 times more stable as calculated from the thermal decay constant at 37 °C. when compared to unmodified factor V.The increase in activity of factor V by thrombin was biphasic after removal of all sialic acid residues. The binding of asialo-factor V to phosphatidyl ethanolamine, as, characterized both by kinetics and by sucrose density gradient ultracentrifugation, resulted in an inactive complex. Double immunodiffusion shows that the sialic acid component of factor V is not necessary for its antigenicity.