Collagen calfskin

Fietzek, P., Rexrodt, W. The covalent structure of collagen. The amino-acid sequence of a2-CH4 of calfskin collagen. Eur. J. Biochem. 59, 113 (1975)... 

Peptides Derived from Tryptic Digestion of the Soluble Collagen of Calfskin... 

Fig. 18. Comparison between the rate of the collagen — gelatin transition for soluble calfskin collagen at 35.9 C, measured as the fractional change in specific viscosity (solid line) and specific rotation (dotted line). (From Doty and Nishihara, 1958.)...

Essentially similar conclusions have been reached by Grassmann et al. (1961) on the basis of an analysis of sedimentation patterns of denatured, acid-extracted calfskin collagen. They propose that the formation of the /3-component arises from cross-linking of two a components which may or may not be identical in amino acid composition, while a third component always present in small amount, the y component, represents a structure in which three a-components are cross-linked together. 

An indication that hexoses are involved in the intramolecular cross-linking is found in the data of Hermann et al. (1959) on the action of periodic, acid on acid-soluble collagen from calfskin (Table X). In this sample approximately 1 mole of HIO4 is used per hexose unit present. If, however, the hexose was linked only in the C-1 position as found in ichthyocol (Blumenfeld et al., 1963b), then 2 moles of HIO4 would be required. This supports the hypothesis that transesterification is involved in the foimation of intramolecular cross-links. Such transesterification will... 

Later analyses of calfskin collagen show two additional amino acid residues, glutamine and asparagine, each present in about 2% concentration (by number of residues). The distinctive groups have been added to the table. 

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