Characterization of fibronectin from fetal human plasma in comparison with adult plasma fibronectin.

Fibronectin was purified from fetal human plasma and characterized in comparison with fibronectin from adult human plasma. Fetal plasma fibronectin had an amino-acid composition, immunological properties, and cell-attachment-promoting activity similar to those of adult plasma fibronectin. However, fetal plasma fibronectin was shown to have a distinct carbohydrate composition which is characterized by the presence of fucose. To ascertain the differences in the carbohydrate moiety, 14C-labeled glycopeptides were prepared and sequentially analyzed with columns of immobilized concanavalin A and lentil lectin. Glycopeptides from fetal plasma fibronectin contained a population of glycopeptides which bound to both lectin gels. Almost all of the glycopeptides in this population lost their ability to bind to lentil lectin upon fucosidase digestion, indicating that fetal plasma fibronectin possesses a substantial amount of fucosylated biantennary glycans. In contrast, glycopeptides from adult plasma fibronectin practically lacked such glycopeptides. Another difference observed was that fetal plasma fibronectin had a larger amount of concanavalin A-unbound glycopeptides than did adult plasma fibronectin. These results indicate the presence of age-related variation in glycosylation of human plasma fibronectin.