Collagen fibrils telopeptides

Ortolani, F., Giordano, M., and Marchini, M. (2000). A model for type II collagen fibrils Distinctive D-band patterns in native and reconstituted fibrils compared with sequence data for helix and telopeptide domains. Biopolymers 54, 448-463. 

Figure 49-24 Pyridtnium cross-links and N-telopeptides of type I collagen. Cross-links occur at two intermolecular sites in the collagen fibril (i) two N-telopeptides are linked to a helical site at residue 930, and (2) two C-te opeptides are linked to helical residue 87.The location and amino acid sequence of the N-telopeptide (NTx) and the C-telopeptide (CTx) and the structures of the free pyridinium cross-links (pyridinoline and deoxypyridinoline) are shown.

The major sources of collagen I for in vitro applications are rat tail tendons, bovine Achilles tendons, and bovine skin. The extraction procedure requires partial solubiUzation of the collagen molecules under acidic conditions and may involve a treatment with pepsin to remove telopeptides and thereby decrease immunogenicity (Mano, 2013). Yet, the latter step may disturb the subsequent self-assembly of the molecules into fibrils (fibrillogenesis) and is therefore not always performed. Of note, collagen II can also be obtained from articular cartilages, but the complexity... 

---