Peptide mapping reveals differences in the non-glycosylated domains of cystic fibrosis and normal tracheobronchial mucins.
Tracheobronchial mucins from lung mucus secretions of healthy individuals and from patients with cystic fibrosis (CF) were purified according to a protocol established in our laboratory. Following digestion of the purified, reduced-alkylated mucin (free of 118 kDa and 70 kDa components) with trypsin-L-1-tosylamido-2-phenylethyl chloromethyl ketone, three fractions (TR-1, TR-2 and TR-3) were observed upon chromatography on a Superose 6 column using FPLC. TR-1 (glycosylated fraction) contained all of the carbohydrate, while TR-2 and TR-3 fractions had no detectable sugars. Comparison of the amino acid composition of TR-1 fractions from normal and CF individuals revealed no significant differences, while the TR-2 fractions from these mucins showed noticeable differences. Peptide mapping of TR-2 fractions from normal and CF mucins was performed on a C18 reverse phase column using FPLC. The peptide maps of normal mucins were markedly different from CF mucins. A greater number of peptides were seen in the TR-2 fractions of normal mucins when compared to CF mucin TR-2 fractions. In addition, normal TR-2 fractions appeared to be comprised of more hydrophobic peptides when compared to CF TR-2 fractions. These data provide evidence of possible structural differences in the non-glycosylated regions of CF and non-CF mucins, since the TR-2 fractions are essentially derived from the T-domains in the "naked" stretches of the mucin polypeptide backbone.
Desai
V C
VC
College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City 73190.
Shankar
V
V
de la Rocha
S R
SR
Sachdev
G P
GP
D000596:Amino Acids / Q000032:analysis; D001980:Bronchi / Q000378:metabolism*; D002241:Carbohydrates / Q000032:analysis; D002850:Chromatography, Gel; D003550:Cystic Fibrosis / Q000378:metabolism*; D006801:Humans; D009077:Mucins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism; D010449:Peptide Mapping; D012016:Reference Values; D013183:Sputum / Q000737:chemistry; D014132:Trachea / Q000378:metabolism*
D000596:Amino Acids; D002241:Carbohydrates; D009077:Mucins