Additional fucosyl residues on membrane glycoproteins but not a secreted glycoprotein from cystic fibrosis fibroblasts

Glycopeptides derived from peripheral membrane glycoproteins of skin fibroblasts of seven patients with cystic fibrosis (CF) had an increase in fucosyl residues when compared with those of seven age, race and sex matched controls (Pediatr Res 1985;19:368-374). To further define these results, the membrane glycopeptides which bound to immobilized lentil lectin and thereby enriched in fucosyl residues linked α1 → 6 to N-acetylglucosamine attached to asparagine, were Pronase digested, partially purified and examined by 500-MHz ¹H-NMR spectroscopy. The CF derived glycopeptides had two different features when compared to those from Controls (1) an increased number of fucosyl residues linked α1 → 6 to the N-acetylglucosamine attached to asparagine and (2) fucosyl residues linked αl → 3 to a branch N-acetylglucosamine. The glycopeptides from both sources were of the di and triantennary type containing sialic acid linked α2 → 3 and α2 → 6 to galactose in an approximate molar ratio of 3:2 and 2:1, from CF and Control, respectively. Glycopeptides derived from a glycoprotein, fibronectin, secreted from CF fibroblasts were also examined by ¹H-NMR spectroscopy and showed no evidence of fucosyl residues linked α1 → 3 to branch N-acetylglucosamine and a lesser percentage of core fucose than found in the peripheral membrane glycopeptides. These results define further the altered fucosylation of the CF peripheral membrane glycoproteins.