[Isolation of fibronectin peptide fragments of various sizes and biological activity using affinity chromatography on...

Plasmin, immobilized on Sepharose, was used for isolation of human blood plasma fibronectin fragments obtained after proteolysis. Under definite conditions the major part of the fibronectin fragments, liberated during proteolysis, remained to be bound to plasmin-Sepharose. As shown by electrophoretic analysis, the fraction of fragments bound to plasmin-Sepharose constituted mainly "heavy" (greater than or equal to 120 kD) peptides and one "light" (29 kD) peptide, while only "light" fragments (less than or equal to 45 kD) were detected in the free unbound fraction. These unbound to plasmin-Sepharose fibronectin fragments were found to stimulate proliferation of human embryonal fibroblasts in cell culture, whereas the plasmin-Sepharose bound peptides did not exhibit any effects on proliferation.