Isolation of fatty acids covalently bound to the gastric mucus glycoprotein of normal and cystic fibrosis patients

Covalently bound fatty acids were found in strictly purified and delipidated gastric mucus glycoprotein of normal and cystic fibrosis individuals. The susceptibility of this linkage to methanolic KOH and hydroxylamine treatment indicated the ester bond between fatty acids and glycoprotein. On the average, 2.9 nmol fatty acid/mg glycoprotein were found in normal samples, and 12.2 nmol/mg glycoprotein in samples derived from cystic fibrosis. In normal gastric mucus glycoprotein the covalently linked fatty acids consisted of hexadecanoate (47.0%), octadecanoate (22.0%), tetracosanoate (5.9%), octadecenoate (14.5%) and tetracosenoate (6.0%). In cystic fibrosis mucus glycoprotein the covalently bound fatty acids were comprised mainly of hexadecanoate (36.5%), octadecanoate (48.7%) and octadecenoate (8.6%). These data indicate that cystic fibrosis gastric mucus glycoprotein is highly acylated and perhaps this is the major defect of glycoproteins in this disease.