title: Solution structure of human von Willebrand factor studied using small angle neutron scattering.
abstract: von Willebrand factor (VWF) binding to platelets under high fluid shear is an important step regulating atherothrombosis. We applied light and small angle neutron scattering to study the solution structure of human VWF multimers and protomer. Results suggest that these proteins resemble prolate ellipsoids with radius of gyration (R(g)) of approximately 75 and approximately 30 nm for multimer and protomer, respectively. The ellipsoid dimensions/radii are 175 x 28 nm for multimers and 70 x 9.1 nm for protomers. Substructural repeat domains are evident within multimeric VWF that are indicative of elements of the protomer quarternary structure (16 nm) and individual functional domains (4.5 nm). Amino acids occupy only approximately 2% of the multimer and protomer volume, compared with 98% for serum albumin and 35% for fibrinogen. VWF treatment with guanidine.HCl, which increases VWF susceptibility to proteolysis by ADAMTS-13, causes local structural changes at length scales <10 nm without altering protein R(g). Treatment of multimer but not protomer VWF with random homobifunctional linker BS(3) prior to reduction of intermonomer disulfide linkages and Western blotting reveals a pattern of dimer and trimer units that indicate the presence of stable intermonomer non-covalent interactions within the multimer. Overall, multimeric VWF appears to be a loosely packed ellipsoidal protein with non-covalent interactions between different monomer units stabilizing its solution structure. Local, and not large scale, changes in multimer conformation are sufficient for ADAMTS-13-mediated proteolysis.
authors.affiliation: Department of Chemical and Biological Engineering, State University of New York, Buffalo, NY 14260, USA.
authors.forename: Indrajeet
authors.initials: I
authors.lastname: Singh
authors.forename: Harish
authors.initials: H
authors.lastname: Shankaran
authors.forename: Mark E
authors.initials: ME
authors.lastname: Beauharnois
authors.forename: Zhihua
authors.initials: Z
authors.lastname: Xiao
authors.forename: Paschalis
authors.initials: P
authors.lastname: Alexandridis
authors.forename: Sriram
authors.initials: S
authors.lastname: Neelamegham
mesh_terms: D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D009502:Neutrons; D011487:Protein Conformation; D012542:Scattering, Radiation; D014841:von Willebrand Factor / Q000737:chemistry* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D014841:von Willebrand Factor