title: Antithrombin properties of C-terminus of hirudin using synthetic unsulfated N alpha-acetyl-hirudin45-65.
abstract: Unsulfated N alpha-acetyl-hirudin45-65 (MDL 27 589), which corresponds to the C-terminus of hirudin1-65, was synthesized by solid-phase methods. The synthetic peptide was able to inhibit fibrin formation and the release of fibrinopeptide A from fibrinogen by thrombin. The catalytic site of thrombin was not perturbed by the synthetic peptide as H-D-Phe-Pip-Arg-pNA hydrolysis (amidase activity) was not affected. The binding of synthetic peptide and thrombin was assessed by isolation of the complex on gel-filtration chromatography. A single binding site with a binding affinity (Ka) of approx. 1.0 X 10(5) M-1 was observed for thrombin-hirudin45-65 interaction. The data suggest that the C-terminal residues 45-65 of hirudin contain a binding domain which recognizes thrombin and yet does not bind to the catalytic site of the enzyme.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000991:Antithrombins; D002417:Cattle; D005337:Fibrin / Q000502:physiology; D005344:Fibrinopeptide A / Q000032:analysis; D006629:Hirudins / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D007700:Kinetics; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D011863:Radioimmunoassay; D013917:Thrombin / Q000502:physiology
chemical_list: D000991:Antithrombins; D006629:Hirudins; D010446:Peptide Fragments; C051299:N(alpha)-acetylhirudin(45-65); D005344:Fibrinopeptide A; D005337:Fibrin; D013917:Thrombin