Structural studies on a collagen-like glycoprotein isolated from lung lavage of normal animal.

A major glycoprotein of Mr = 36 000 has been isolated from lung lavage of normal rabbit and purified to homogeneity by gel chromatography. The glycoprotein was found to contain 4 residues hydroxyproline, 50 residues glycine, 3 residues methionine, 2.6 mol sialic acid, 4.0 mol galactose, 5.0 mol mannose, 0.9 mol fucose and 7.0 mol glucosamine. Cyanogen bromide treatment of the glycoprotein resulted in four peptides with molecular weights of 18 000, 12 000, 5000 and 1000, three of the peptides containing hydroxyproline and two of the peptides containing carbohydrates. Partial NH2-terminal amino acid sequence analysis on one of the cyanogen bromide peptides (Mr = 18 000) indicated the presence of -Gly-Pro-Hyp-Gly- sequence in the peptide chain, suggesting that collagen-like region(s) may be present in this glycoprotein.