The structural elements of hirudin which bind to the fibrinogen recognition site of thrombin are exclusively located within its acidic C-terminal tail.
Six lysyl residues of human thrombin (LysB21, LysB52, LysB65, LysB106, LysB107 and LysB154) have been previously shown to participate in the binding site of hirudin, a thrombin-specific inhibitor [(1989) J. Biol. Chem. 264, 7141-7146]. In this report, we attempted to delineate the region of hirudin which binds to these basic amino acids of thrombin. Using the N-terminal core domains (r-Hir1-43 and r-Hir1-52) derived from recombinant hirudins and synthetic C-terminal peptides (Hir40-65 and Hir52-65)--all fragments form complexes with thrombin--we are able to demonstrate that the structural elements of hirudin which account for the shielding of these 6 lysyl residues are exclusively located within the acidic C-terminal region. Since hirudin C-terminal peptides were shown to bind to a non-catalytic site of thrombin and inhibit its interaction with fibrinogen [(1987) FEBS Lett. 211, 10-16], our data consequently imply that these 6 lysyl residues are constituents of the fibrinogen recognition site of thrombin.
Chang
J Y
JY
Pharmaceuticals Research Laboratories, Ciba-Geigy Ltd., Basel, Switzerland.
Ngai
P K
PK
Rink
H
H
Dennis
S
S
Schlaeppi
J M
JM
D000595:Amino Acid Sequence; D001665:Binding Sites; D005340:Fibrinogen / Q000378:metabolism*; D006629:Hirudins / Q000378:metabolism*; D006801:Humans; D008239:Lysine; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011994:Recombinant Proteins; D013917:Thrombin / Q000378:metabolism*
D006629:Hirudins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D005340:Fibrinogen; D013917:Thrombin; D008239:Lysine