title: The binding of calcium to human fibronectin.
abstract: The binding of calcium to human plasma fibronectin has been measured by equilibrium dialysis at 25 degrees in 0.1 M NaCl 50mM Tris HCL, pH 7.4. Curve fitting of the binding data indicates that fibronectin has two strong calcium binding sites per chain (Mr 220,000), KD = 1.3 mM and approximately 12 weak sites, KD = 2.3 mM. No significant displacement of bound calcium by magnesium was observed at magnesium concentrations up to 1 mM. Calcium binding to a pair of tryptic fragments of fibronectin (Mr congruent to 160,000 and 180,000) that bind to gelatin has also been investigated. These fragments have a single class of calcium binding sites, with 2.2 sites per chain, KD = 1.1 mM. Negligible calcium binding to tryptic fragments derived from other regions of the fibronectin molecule was observed.
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000097:blood*; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D008027:Light; D011485:Protein Binding; D012542:Scattering, Radiation
chemical_list: D005353:Fibronectins; D002118:Calcium