title: Anticoagulant peptides: nature of the interaction of the C-terminal region of hirudin with a noncatalytic binding site on thrombin.
abstract: A series of 20 C-terminal fragment analogues of the anticoagulant peptide hirudin were synthesized by solid-phase techniques in order to investigate the nature of the thrombin-hirudin interaction. Inhibition of plasma fibrin clot formation by thrombin in vitro was used as a measure of anticoagulant activity. In the minimum region necessary for detectable anticoagulant activity, hirudin56-64, positions Phe56, Glu57, Ile59, Pro60, and Leu64 are sensitive to modification. These residues are apparently important for direct interaction with thrombin or for maintaining a favorable conformation for the interaction. On the basis of conformational analysis of this region by computational methods, a "kinked" amphipathic alpha-helical structure, which orients all of the residues most critical for activity on one face of the helix, is proposed.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D006629:Hirudins / Q000378:metabolism*; D011487:Protein Conformation; D013917:Thrombin / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D006629:Hirudins; D013917:Thrombin