Collagen components

The major non-collagenous components of the dentin matrix are highly-phosphorylated proteins, phosphoryns, with many phosphoserine and aspartate residues (Butler et al., 1992). Dentin contains fewer proteoglycans than predentin. The proteoglycans from predentin are degraded upon mineralization, while small proteoglycans and phosphoryns are excreted by odontoblasts and incorporated into dentin (Goldberg et al., 1987 Linde, 1989). 

Carmichael DJ, Dodd CM and Veis A (1977) The solubilization of bone and dentine collagens by pepsin. Effect of cross-linkages and non-collagen components. Biochim Biophys Acta 491, 177-192. 

In the tanning process hides are first washed or soaked, hair and keratinous debris are removed, bated (enzymes are used to break down non-collagenous components, which are washed out) and the hide is acid-pickled to prepare for the addition of the chromium salt. Contemporary processes are exclusively based on one-bath procedures and utilize chromium(III). The older two-bath process is now obsolete, mainly because it involved the in situ reduction of chromate, a major environmental and toxicological hazard (cf. chromate toxicity p. 947) to chromium(III) on the hide. A useful review of the history of chromium tannage processes is available.1205... 

A better understanding of the structure of collagen IV molecules explains some previous observations. The occurrence of the 7 S domain and nonhelical interruptions in the molecule can explain in part the heterogeneous mixture of collagenous components isolated from basement membrane, particularly when pepsin or other proteases are used to solubilize the protein. The molecules isolated from lathyritic basement membrane by acid extraction are truncated and lack the 7 S domain presumably due to cleavage by endogenous proteases. 

Acid etching pretreatment of dentin prior to application of a resin restorative leaves the collagenous component of this substrate substantially untouched. The collagen at the dentin surface interferes with the mechanical adhesion of the hydroxyapatite, (the inorganic constituent of dentin) to the adhesive. Thus, in contrast to its successful use with enamel, etching pretreatment produces a bond between dentin and restorative resin that is too weak to withstand the forces encountered at the interface under clinical conditions. 

The collagen component forms a network of fine fibrils that give shape to the cartilage. The proteoglycans embedded in the cartilage are responsible for its compressibility and its deformability. 

Liotta, L.A., et al.. Effect of plasminogen activator (urokinase), plasmin, and thrombin on glycoprotein and collagenous components of basement membrane. Cancer Res, 1981. 41(11 Ptl) p. 4629-36. 

The specialised (type IV) collagens of basement membranes are also extensively glycosylated and there is still some uncertainty as to whether they can contain longer saccharides, though the general view is that these are present in non-collagenous components of these structures. 

Chroma.tography Distribution of Collagen Components Miller and Rhodes, 1982... 

Patients with a history of dietary beef allerg) should be carefully evaluated before injectable bovine collagen therapy, since it is possible that tlie collagen component of the beef may be causing the allergy. More than one skin test is highly recommended prior to treating these patients . 

---