Collagen stabilization, hydrogen bonds

Collagen triple helices are stabilized by hydrogen bonds between residues in dijferent polypeptide chains. The hydroxyl groups of hydroxyprolyl residues also participate in interchain hydrogen bonding. Additional stability is provided by covalent cross-links formed between modified lysyl residues both within and between polypeptide chains. 

Figure 19.12 Water helps to stabilize collagen by forming inter- and intra-hydrogen bonds with hydrophilic residues. (From Nyman et al., 2005. Copyright 2003, with permission from Elsevier.)...

Hydroxyproline and hydroxylysine Collagen contains hydroxy proline (hyp) and hydroxylysine (hyl), which are not present in most other proteins. These residues result from the hydroxylation of some of the proline and lysine residues after their incorporation into polypeptide chains (Figure 4.6). The hydroxylation is, thus, an example of posttranslational modification (see p. 440). Hydroxy proline is important in stabilizing the triple-helical structure of colla gen because it maximizes interchain hydrogen bond formation. 

Figure 2.21. Stabilization of collagen triple helix. The diagram shows hydrogen bonding between the amide hydrogen in position 4 on chain A and the carbonyl oxygen in position 2 on chain B. A second water-mediated hydrogen bond occurs when hydroxyproline is present in position 3 on chain A between the carbonyl oxygen in position 1 on chain A and the amide hydrogen in position 2 on chain B.

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