Effect of iron ions on functional activity of thrombin.

The kinetics of thrombin inhibition by irons ions was studied in the thrombin time test with normal plasma. The kinetic and concentration characteristics for recovery of thrombin activity by desferal were evaluated at various periods of thrombin incubation with iron ions. The thrombin time test showed that incubation of thrombin with iron sulfate in a final concentration of 200 microM for 25-35 min is followed by the loss of thrombin activity. Pretreatment of iron-containing incubation system with desferal was shown to decelerate the process of thrombin inactivation. The kinetic characteristics for recovery of thrombin activity by 2 mM desferal were estimated at various periods after addition of iron sulfate in the inhibitory dose. The effect of reversibility was shown to depend on the time of thrombin preincubation with iron. Incomplete recovery of thrombin activity after increasing the time of incubation with iron (more than 30 min) was probably related to oxidative modification of thrombin.