title: Solution structure of human plasma fibronectin using small-angle X-ray and neutron scattering at physiological pH and ionic strength.
abstract: Human plasma fibronectin has been investigated at physiological pH and ionic strength, by using small-angle X-ray and neutron scattering techniques. The results indicate that the molecule is disc shaped with an axial ratio of about 1:10. In fact, an ellipsoid of revolution with semiaxes a = 1.44 nm and b = c = 13.8 nm is in agreement with the experimental scattering data, and can also fully explain the rather extreme hydrodynamic parameters reported for fibronectin. The X-ray data gave a radius of gyration of 8.9 nm and a molecular weight of 510,000, whereas the neutron data gave slightly larger values, 9.5 nm and 530,000, respectively. From the volume of the best fitting ellipsoid we obtain a degree of hydration of 0.61 g H2O/g protein (dry weight). Neutron data, recorded at different D2O concentrations in the solvent, gave a match point of 43% D2O, which indicates that approximately 80% of the hydrogens bound to oxygen and nitrogen are exchangeable.
mesh_terms: D005353:Fibronectins / Q000097:blood*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D011487:Protein Conformation; D012542:Scattering, Radiation; D012996:Solutions; D014961:X-Ray Diffraction; D014965:X-Rays
chemical_list: D005353:Fibronectins; D012996:Solutions