Reversible inactivation by dextran sulfate of bovine thrombin in dilute solution.

Dextran sulfate (DS)-enhanced inactivation of alpha-thrombin was faster at pH 6 than at pH 8 in the absence of NaCl. Substrate protected only partly thrombin from inactivation by DS at pH 6. Some amidolytic activity of alpha-thrombin inactivated by DS was restored time-dependently by the addition of NaCl. Moreover, beta and gamma-thrombin, and other intermediates were not formed from alpha-thrombin with DS-enhanced inactivation. All these results indicate that autolysis of alpha-thrombin in dilute solution is not responsible for enhancement of reversible inactivation of alpha-thrombin by DS.