title: Physical evidence for the assembly of A and B chains of human placental collagen in a single triple helix.
abstract: Native collagen molecules containing A and B chains were isolated from pepsin-solubilised human chorionic and amniotic membrane extracts by fractional salt precipitation and DEAE-cellulose chromatography. They exhibited a circular dichroism spectrum, and a melting curve, characteristic for a triple-helical structure. Electron microscopical investigations of their segment-long-spacing crystallites revealed a molecule similar to those of the interstitial types I, II and III collagens. After denaturation, the A and B chains were separated by DEAE-cellulose chromatography and were consistently recovered in a ratio of 1:2. Renaturation experiments indicated that only the B chains are able to reform triple-helical molecules which are stable under conditions in vivo. The data support a molecular formula A(B)2 for the native collagen molecule.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000650:Amnion; D002823:Chorion; D002942:Circular Dichroism; D003094:Collagen / Q000032:analysis*; D005260:Female; D006801:Humans; D010446:Peptide Fragments / Q000032:analysis*; D010920:Placenta; D011247:Pregnancy; D011487:Protein Conformation; D011489:Protein Denaturation
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D003094:Collagen