title: Isolation and characterization of a collagen binding domain in human von Willebrand factor.
abstract: von Willebrand factor binds to fibrillar type I collagen in a rapid, temperature-independent, reversible, specific, and saturable manner. Evaluation of binding isotherms by Scatchard-type analysis demonstrated that 6-18 micrograms of von Willebrand factor bind per mg of collagen, with Ka between 2 and 8 X 10(8) M-1. Five distinct tryptic fragments, purified under denaturing and reducing conditions and representing over 75% of the molecular mass of the von Willebrand factor subunit, were tested for their capacity to inhibit the von Willebrand factor-collagen interaction. Complete inhibition was obtained with a 52/48-kDa fragment at a concentration of approximately 1 microM. The location of this fragment in the subunit was established to be between Val-449 and Lys-728. Fifteen monoclonal antibodies against the 52/48-kDa fragment inhibited von Willebrand factor binding to collagen. Six antibodies against other portions of the von Willebrand factor subunit had no inhibitory effect. The tryptic fragment was a competitive inhibitor of von Willebrand factor binding to collagen and, therefore, recognizes the same interaction site as the intact molecule. These studies precisely define a domain in the von Willebrand factor subunit that interacts with type I collagen.
mesh_terms: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D001665:Binding Sites; D003094:Collagen / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D013816:Thermodynamics; D014357:Trypsin; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D010446:Peptide Fragments; D014841:von Willebrand Factor; D003094:Collagen; D014357:Trypsin