Mammals, collagen

A different type of helix is present in collagen, the most abundant protein of mammals. Collagen is the n jain fibrous component of skin, bone, tendon, cartilage, and teeth. This extracellular protein is a rod-shaped mol-ecule, about 3000 A long and only 15 A in diameter. It contains three helical polypeptide chains, each nearly 1 ()()() residues long. Glycine appears at every third residue in the amino acid sequence, and the sequence glycine-... 

M.p. 190-192 C. The enolic form of 3-oxo-L-gulofuranolactone. It can be prepared by synthesis from glucose, or extracted from plant sources such as rose hips, blackcurrants or citrus fruits. Easily oxidized. It is essential for the formation of collagen and intercellular material, bone and teeth, and for the healing of wounds. It is used in the treatment of scurvy. Man is one of the few mammals unable to manufacture ascorbic acid in his liver. Used as a photographic developing agent in alkaline solution. 

In this paper, I attempt to refine the predictable isotopic differences between collagen and carbonate that can be found in modem faunas from temperate and cold areas, using samples from Europe, Siberia and northwestern North America. Some of the results presented here have been published previously (Bocherens et a/. 1991a, 1991b, 1994, 1995a, 1995b, 1 6 Bocherens and Mariotti 1992 Fizet et al. 1995) but additional new data are reviewed as well in order to present a new synthesis. This should provide a framework that can be used to assess the quality of preservation of the isotopic signatures in Pleistocene mammal bones and teeth from these areas. 

Figure 4.2. 8 N values of mammal bone collagen in Cj plant ecosystems.

Figure 4.5. 8 C and 8 N values of bone collagen from Marillac mammals (-45,000 BP) compared with those of recent mammals from cold and temperate areas (average 1 s.d.). Isotopic abundances of Marillac mammals are from Fizet et al. (1995).

The following differences have been observed in modern mammals from cold and temperate areas with no C4 plants a slight enrichment in C in collagen between herbivores and carnivores a clear difference in carbonate hydroxylapatite 8 C values between herbivores and carnivores (including bears), and thus a difference between A Cvalues of herbivores and carnivores a clear enrichment in N between herbivore and carnivore bone collagen. 

Figure 4.10. Differences in 6 N values between bone and dentine collagen from Pleistocene and recent mammals. Isotopic abundances are from Bocherens et al. (1994, 1995b) and this paper.

Bocherens, H., Pacaud, G., Lazarev, P. and Mariotti, A. 1996 Stable isotope abundances ( C, N) in collagen and soft tissues from Pleistocene mammals from Yakutia. Implications for the paleobiology of the mammoth steppe. Palaeogeography, Palaeoclimatolology, Palaeoecology 126 31. ... 

Table 6.2. Phosphate 8 0 and collagen 5 C values of tooth enamel and bone of mammals from Sibiloi National Park, East Turkana, Kenya.

Collagen, the major component of most connective tissues, constimtes approximately 25% of the protein of mammals. It provides an extracellular framework for all metazoan animals and exists in virmally every animal tissue. At least 19 distinct types of collagen made up of 30 distinct polypeptide chains (each encoded by a separate gene) have been identified in human tissues. Although several of these are present only in small proportions, they may play important roles in determining the physical properties of specific tissues. In addition, a number of proteins (eg, the Clq component of the complement system, pulmonary surfactant proteins SP-A and SP-D) that are not classified as collagens have... 

Figure 8.7 Relationship between bone collagen carbon isotope ratio and latitude for modern carnivorous terrestrial mammals. The regression equation is given as <513C = -0.20 ( 0.03) x latitude - 9.7 ( 1.0), with r2 = 0.75. Reproduced from Kelly (2000 7) by permission of the National Research Council Canada Research Press.

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