Fluid shear induces conformation change in human blood protein von Willebrand factor in solution

Biophys J. 2009 Mar 18;96(6):2313-20. doi: 10.1016/j.bpj.2008.12.3900.

Abstract

Many of the physiological functions of von Willebrand Factor (VWF), including its binding interaction with blood platelets, are regulated by the magnitude of applied fluid/hydrodynamic stress. We applied two complementary strategies to study the effect of fluid forces on the solution structure of VWF. First, small-angle neutron scattering was used to measure protein conformation changes in response to laminar shear rates (G) up to 3000/s. Here, purified VWF was sheared in a quartz Couette cell and protein conformation was measured in real time over length scales from 2-140 nm. Second, changes in VWF structure up to 9600/s were quantified by measuring the binding of a fluorescent probe 1,1'-bis(anilino)-4-,4'-bis(naphthalene)-8,8'-disulfonate (bis-ANS) to hydrophobic pockets exposed in the sheared protein. Small angle neutron scattering studies, coupled with quantitative modeling, showed that VWF undergoes structural changes at G < 3000/s. These changes were most prominent at length scales <10 nm (scattering vector (q) range >0.6/nm). A mathematical model attributes these changes to the rearrangement of domain level features within the globular section of the protein. Studies with bis-ANS demonstrated marked increase in bis-ANS binding at G > 2300/s. Together, the data suggest that local rearrangements at the domain level may precede changes at larger-length scales that accompany exposure of protein hydrophobic pockets. Changes in VWF conformation reported here likely regulate protein function in response to fluid shear.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anilino Naphthalenesulfonates
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Models, Molecular
  • Neutrons
  • Protein Conformation
  • Scattering, Radiation
  • Stress, Mechanical
  • von Willebrand Factor / chemistry*

Substances

  • Anilino Naphthalenesulfonates
  • von Willebrand Factor
  • 5,5'-bis(8-(phenylamino)-1-naphthalenesulfonate)