Decreased heparin sensitivity of cycholhexanedione-modified thrombin.

Modification of 5--6 arginine residues of thrombin with 1,2-cyclohexanedione has resulted in the selective abolition of the heparin sensitivity of the enzyme's reaction with antithrombin-III, whereas the antithrombin-III sensitivity of native and modified thrombin was indistinguishable. It is suggested that heparin accelerates the thrombin antithrombin-III reaction by interacting with thrombin.