Amino collagen, chain

The part of non-imino acid-containing tripeptides amounts to nearly 50%. It is astonishing that at some places in the collagen chain, containing 1044 amino acid units, such sequences are accumulated, forming imino add-free ranges of remarkable length. 

Every third amino acid in most collagen chains is glycine, in triplet repeats of the sequence Gly-Pro-X and Gly-X-hydroxyproline, where X = any amino acid. 

Fig. 2. Kinetics of cross-linking of chondroitin 6-sulfate, a glycosaminoglycan (GAG), to collagen following exposure to 105 °C under 6.7 Pa (50 mtorr). The mechanism of cross-linking is most probably interchain amide condensation involving e-amino groups of lysyl residues on collagen chains with carboxylic groups on glucuronic acid residues in neighboring GAG chains (From [30] with permission).

The decrease in enzyme sorption by the chemically modified membrane implies that under these experimental conditions, the lysyl E-amino groups function as principle receptor or binding sites for enzyme protein (at least for E. coli g-galactosidase) and that the complexation mechanism involves interaction of the lysyl residues of collagen with enzyme amino acid chains as an initial step in the formation of a stable network of physicochemical bonds. 

Figure 2.45 Amino acid sequence of a part of a collagen chain. Every third residue is a glycine. Proline and hydroxyproline also are abundant.

Every third amino acid in the collagen chain is glycine. It is important to the structure because the triple-stranded helix forms as a result of interchain hydrogen bonding involving glycine. Thus, every third amino acid on one strand is in very close contact with the other two strands. Glycine has another... 

The numerous cross-linkages found in collagen are the result of the oxidation of lysine and hydroxylysine to a-amino adipic acid 8-semialde-hyde (allysine) and 8-hydroxy a-amino adipic acid 8-semialdehyde (hy-droxyallysine), respectively, following the assemblage of the collagen chains into the macromolecular structure (Equations 4 and 5) ... 

Table 2. Amino Acid Compositions for Various Collagen Chains ...

Table 27.5 Amino add composition of the human collagen chains (residues/1000 total residues)...

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