Two plasma fibronectin fragments with different gelatin-binding properties

Abstract

Two subtilisin-generated fragments of human plasma fibronectin exhibit significantly different gelatin affinities. One fragment of 60 kdaltons elutes from gelatin-Sepharose, after intact fibronectin, with pH 5.5, 50 mM citrate, 0.1 M NaCl. A 40 kdalton fragment, which can be derived from the 60 kdalton fragment, remains bound to gelatin under the same conditions. Furthermore, upon urea gradient elution, the 60 kdalton fragment dissociates from gelatin before the smaller fragment. Of the two fragments, the 60 kdalton fragment also demonstrates affinity for heparin. Identical amino-terminal sequences for the two fragments indicate that the heparin-binding activity resides in the difference region at the carboxyl-terminal of the 60 kdalton fragment.