Collagen conformation

Eliades, G., Vougiouklakis, G., and Palaghias, G. (1999) Effect of dentin primers on the morphology, molecular composition and collagen conformation... 

Wess, T.J., et al. Type 1 collagen packing, conformation of the triclinic unit cell. J. Mol. Biol. 248 487-493, 1995. 

The ability of these peptidomimetic collagen-structures to adopt triple helices portends the development of highly stable biocompatible materials with collagenlike properties. For instance, it has been found that surface-immobilized (Gly-Pro-Meu)io-Gly-Pro-NH2 in its triple-helix conformation stimulated attachment and growth of epithelial cells and fibroblasts in vitro [77]. As a result, one can easily foresee future implementations of biostable collagen mimics such as these, in tissue engineering and for the fabrication of biomedical devices. 

M. Collagen-based stmctures containing the peptoid residue N-isobutylglycine (Jtdeu). 6. Conformational analysis of Gly-Pro-Nleu sequences by NMR,... 

The collagen shield, fabricated from procine scleral tissue, is a spherical contact lens-shaped film whose thickness can be made to vary from 0.027 to 0,071 mm. It has a diameter of 14.5 mm and a base curve of 9 mm. Once the shield is hydrated by tear fluid and begins to dissolve, it softens and conforms to the corneal surface. Dissolution rates can be varied from 2 to as long as 72 hr by exposing the shields to ultraviolet radiation in order to achieve varying degrees of crosslinking. 

After secretion from the cell, certain lysyl residues of tropoelastin are oxidatively deaminated to aldehydes by lysyl oxidase, the same enzyme involved in this process in collagen. However, the major cross-links formed in elastin are the desmosines, which result from the condensation of three of these lysine-derived aldehydes with an unmodified lysine to form a tetrafunctional cross-hnk unique to elastin. Once cross-linked in its mature, extracellular form, elastin is highly insoluble and extremely stable and has a very low turnover rate. Elastin exhibits a variety of random coil conformations that permit the protein to stretch and subsequently recoil during the performance of its physiologic functions. 

The Pn conformation of poly-L-proline (PP) or collagen in the solid state could be identified from X-ray fiber diffraction results (Cowan and McGavin, 1955). Persistence of this basic structure in solution was inferred from the resemblance between the CD spectra of solutions and films of the polypeptide. The CD spectra of the charged forms of PGA and PL closely resemble that of Pn (compare Fig. IB, 1C, and ID) however, these spectra differ significantly from those of PP peptides at high temperature or in the presence of high concentration of salts... 

Krimm, 1968a,b Mattice and Mandelkern, 1971 Krimm and Tiffany, 1974). This conformation is similar to that of a single strand from collagen, with average backbone dihedrals of (0,0) = ( 75°, +145°). These dihedrals lead to an extended left-handed helical conformation with precisely three residues per turn and 9 A between residues i and i + 3 (measured Cft to C/3). A cartoon of a seven-residue alanine peptide in this conformation is shown in Figure 1. Notably, backbone carbonyl and amide groups point perpendicularly out from the helical axis into the solvent and are well-exposed. 

Traditional methods for fabricating nano-scaled arrays are usually based on lithographic techniques. Alternative new approaches rely on the use of self-organizing templates. Due to their intrinsic ability to adopt complex and flexible conformations, proteins have been used to control the size and shape, and also to form ordered two-dimensional arrays of nanopartides. The following examples focus on the use of helical protein templates, such as gelatin and collagen, and protein cages such as ferritin-based molecules. 

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