Triple helix formation and disulphide bonding during the biosynthesis of glomerular basement membrane collagen

Abstract The 14 C-collagen synthesised by isolated rat glomeruli during a 2h labelling period with [ 14 C]proline was found to be digested by chymotrypsin at 25°C suggesting that it was in a random coil form. After a 4h chase period, the 14 C-polypeptides were resistant to proteolysis indicating that they were in a triple helical conformation. Gel filtration in sodium dodecylsulphate under reducing and non-reducing conditions suggested that the extent of resistance to digestion by chymotrypsin was closely related to the extent of inter-chain disulphide bond formation. The 14 C-collagen was found to be composed of three identical polypeptide chains which were linked by intra-molecular disulphide bonds within the chymotrypsin-resistant triple-helical region of the molecule.