title: Single-molecule force measurements of the polymerizing dimeric subunit of von Willebrand factor.
abstract: Von Willebrand factor (VWF) multimers are large adhesive proteins that are essential to the initiation of hemostatic plugs at sites of vascular injury. The binding of VWF multimers to platelets, as well as VWF proteolysis, is regulated by shear stresses that alter VWF multimeric conformation. We used single molecule manipulation with atomic force microscopy (AFM) to investigate the effect of high fluid shear stress on soluble dimeric and multimeric forms of VWF. VWF dimers are the smallest unit that polymerizes to construct large VWF multimers. The resistance to mechanical unfolding with or without exposure to shear stress was used to evaluate VWF conformational forms. Our data indicate that, unlike recombinant VWF multimers (RVWF), recombinant dimeric VWF (RDVWF) unfolding force is not altered by high shear stress (100dynes/cm^{2} for 3 min at 37^{∘}C). We conclude that under the shear conditions used (100dynes/cm^{2} for 3 min at 37^{∘}C), VWF dimers do not self-associate into a conformation analogous to that attained by sheared large VWF multimers.
authors: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors: Sithara S
authors: SS
authors: Wijeratne
authors: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors: Jingqiang
authors: J
authors: Li
authors: Thrombosis Division, Section of Cardiovascular Sciences, Department of Medicine, Baylor College of Medicine, Houston, Texas 77005, USA.
authors: Hui-Chun
authors: HC
authors: Yeh
authors: Department of Bioengineering, Rice University, Houston, Texas 77005, USA.
authors: Leticia
authors: L
authors: Nolasco
authors: Puget Sound Blood Center and Division of Hematology, Department of Medicine, University of Washington, Seattle, Washington 98104, USA.
authors: Zhou
authors: Z
authors: Zhou
authors: Thrombosis Division, Section of Cardiovascular Sciences, Department of Medicine, Baylor College of Medicine, Houston, Texas 77005, USA.
authors: Angela
authors: A
authors: Bergeron
authors: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
authors: Eric W
authors: EW
authors: Frey
authors: Department of Bioengineering, Rice University, Houston, Texas 77005, USA.
authors: Joel L
authors: JL
authors: Moake
authors: Puget Sound Blood Center and Division of Hematology, Department of Medicine, University of Washington, Seattle, Washington 98104, USA.
authors: Jing-fei
authors: JF
authors: Dong
authors: Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.|Department of Bioengineering, Rice University, Houston, Texas 77005, USA.
authors: Ching-Hwa
authors: CH
authors: Kiang
mesh_terms: D057809:HEK293 Cells; D006801:Humans; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D058105:Polymerization; D055503:Protein Multimerization; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry; D013314:Stress, Mechanical; D014841:von Willebrand Factor / Q000737:chemistry*
chemical_list: D011994:Recombinant Proteins; D014841:von Willebrand Factor