Collagen helical structure

Collagen-like (ColQ) tailed forms or asymmetric multimers Characterized by triple helical structure of three collagenic subunits Q, each associated with... 

Fig. 4. Helical structure of collagen, typical amino acid sequence within a collagen strand, and exchangeable versus non-exchangeable hydrogen atoms in an individual leucine molecule (Gly - glycine. Pro - Proline, Leu - leucine. Hyp - hydroxyproline.

M., and Goodman, M. Triple helical stabilities of guest-host collagen mimetic structures. Bioorg. Med. Chem. 1999, 7, 153-160. 

AH collagen types have a triple helical structure. In... 

Cohen (4) has suggested that the high equilibrium specific rotation of gelatin at low temperature is due to a partial regaining of the helical structure of collagen. In order to regain such a structure, it would be necessary to impose severe restrictions on the molecule. As pointed out by Ferry and Eldridge (5),... 

Thus, the classical pleated /1-sheet structures have now been supplemented by several new /1-structural fibrous folds that have been established by X-ray crystallographic studies. As a consequence, today, the /1-fibrous folds represent a more diverse class of fibrous structures than those defined by the a- or collagen-helices. 

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. 

The remainder of Section 14 deals with triple helices and collagen mimetic structures (Sections 14.2.3.1 and 14.2.4). A description of routes is included which covers the synthesis of triple-helical structures using template (scaffolds) from a Lys-Lys dimer (Section 14.2.4.1), Glu-Glu dimer (Section 14.2.4.2), and appropriate Cys-Cys branches (Section 14.2.4.3). The syntheses were carried out using solid-phase techniques. A scaffold (template) using the Kemp triacid is also presented (Section 14.2.4.4). Lastly, a chemoselective ligation is presented which joins appropriately defined reaction sites (Section 14.2.4.5).[23]... 

Solid-phase assembly of triple-helical peptides containing (Gly-Pro-Hyp)n sequences using, as a template, Kemp s triacid (KTA) is shown in Scheme 13.[56] Two synthetic routes are used to prepare template-assembled collagen-based structures composed of Gly-Pro-(iBu)Gly sequences. Both routes involve the attachment of the template derivative KTA-(Gly-OH)3 to the N-termini of peptide-peptoid chains. The first route is the solid-phase method as described for the (Gly-Pro-Hyp)n sequences. The second method is to cleave the peptide-peptoid chains from the resin and connect them to the template in soln. 

Inouye, K., Sakakibara, S., and Prockop, D.J. (1976). Effects of the stereo-configuration of the hydroxyl group in 4-hydroxyproline on the triple-helical structures formed by homogenous peptides resembling collagen. Biochim. Biophys. Acta 420, 133-141. 

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