Title : Structure and stability of the triple-helical
domains of human collagen XIV
Abstract :
- Two triple-helical domains , Col 1 and Col 2, were obtained from a pepsin digest of human placental collagen XIV and separated from each other under nondenaturing conditions
- Edman degradation demonstrated 106 amino acids residues in the Col 1 and 149 residues in the Col 2 domain. residues in the Col 2 domain
- All except one of the 37 prolines in the Yaa position of the Gly-Xaa-Yaa triplets were completely hydroxylated to 4-hydroxyproline, and there were three imperfections in the triplet repeat
- Partial or complete hydroxylation and glycosylation were found for all seven lysines lysines in the Yaa position
- Domain Col 1 was joined by disulfide bonds into a trimer, while Col 2 appeared as a mixture of monomers and disulfide-linked dimers
- Circular dichroic spectra were typical for the collagen triple helix and revealed relatively high melting temperatures for Col 1 (38 degrees C) and Col 2 (43 degrees C)
- An almost perfect refolding of the triple helix was observed for Col 1 but not for Col 2, emphasizing the importance of disulfide bonds for the folding kinetics and in part the stability of the triple helix
- Circular dichroic spectra of the large nontriple helical domain , NC3, of collagen XIV indicated 11% alpha helix and 63% beta structure
- Comparative melting profiles of NC3 and intact collagen XIV indicated that the triple helices in intact collagen XIV have a melting temperature of 44 degrees C