[α1(III)]3 Human Skin Collagen

Abstract

Human dermis was digested with pepsin under conditions that maintain the helical conformation of the bulk of the collagen.Molecules containing (rl(II1) chains were separated from [al(I)]& collagen by differential salt precipitation at pH '7.5, with the use of the peptides produced by CNBr cleavage to monitor the composition of each fraction.The isolated molecules are composed of three al(IJ1) chains, and these chains are cross-linked by disulfide bonds.Exposure to dithiothreitol liberates the three apparently identical chains, and these elute on carboxymethylcellulose chromatography at a position intermediate between al(I) and (r2.The pepsin-resistant portion of these chains is the same size as that of previously isolated collagen chains.Human dermis was also digested with CNBr, and resultant al(I) and al(II1) peptides were separated chromatographically.The relative quantities of these peptides indicate that al(II1) chains predominate in early fetal skin, but by birth and in later life al(I) chains are approximately 3 times as plentiful.Collagen extracted from human skin has been well characterized in its chain composition (2) and also at the level of CNBr peptides (3, 4).This molecule is composed of two