Collagen, composites with

Finally, collagen can form a variety of collagen composites with other water-soluble materials. Ions, peptides, proteins, and polysaccharides can all be uniformly incorporated into a collagen matrix. The methods of composite formation include ionic and covalent bonding, entrapment, entanglement, and co-precipitation. A two-phase composite can be formed between collagen, ceramics, and synthetic polymers for specific biomedical applications. 

The ultraviolet absorbance of many proteins is due to the presence of amino acids with aromatic side chains. Gelatin, a derivative of collagen (Chap. 4), has an unusual composition, with a low proportion of aromatic amino acids. 

Very recently, Martin et al. (1963) found a much slower incorporation of C -glycine into the /3-components prepared from lathyritic collagen compared with normal collagen, as well as the lesser amounts of the /3-com-ponent found in the former case. They could detect no differences in the amino acid compositions of corresponding subunits isolated from lathyritic and normal collagens. 

Newly formed collagen extracted with cold, aqueous NaCl solutions consists of three equal-sized chains (a-components) of two different composition types ( -l and -2). The two chains of similar composition are the a-1 chains. The a-2 chain differs from the a-1 in a number of amino acids, particularly hydroxyproline, proline, lysine, and histidine (26). As the collagen molecule matures, the a-chains crosslink intramo-lecularly in pairs this older protein can be readily extracted with acidic solutions such as dilute acetate and citrate buffer, but not with salt solutions. The crosslinked chains are called /3 components the crosslinks are probably covalent bonds (26) that arise by condensation of the side chains of strategic lysyl residues after enzymatic oxidative deamination. Older collageil also forms intermolecular bonds, but the nature of this crosslink has not yet been determined (27). 

Mehlisch, D.R., Leider, A.S., and Roberts, W.E., Histologic evaluation of the bone/graft interface after mandibular augmentation with hydroxylapatite/pnrified fibrillar collagen composite implants. Oral Surg. Oral Med. Oral Pathol., 70, 685, 1990. 

Natural leather is produced from the hides of animals by cross-linking the collagen protein contained in the hide. On the other hand, synthetic leathers are synthetic polymer composites with leatherlike properties. 

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