Isolation of type III collagen from human adult parenchymal lung tissue

The isolation and characterization of type III collagen from adult human lung parenchyma are described. The identity of this molecule as type III collagen has been established on the basis of (a) demonstration of intramolecular disulfide cross-links in the helical portion of the molecule, (b) amino acid analysis characteristic for type III collagen, and (c) composition and size of isolated cyanogen bromide peptides alpha1(III)-CB3, alpha1(III)-CB5, and alpha1(III)-CB8. The molecular weight of lung alpha1(III) was determined as 93 000 by Agarose chromatography, but its electrophoretic mobility on sodium dodecyl sulfate-polyacrylamide gels was slower than that of type I alpha chains which also have a molecular weight of 93 000.