title: Intermolecular cross-linking and stereospecific molecular packing in type I collagen fibrils of the periodontal ligament.
abstract: A trypsin digest of denatured NaB3H4-reduced native bovine periodontal ligament was prepared and fractionated by gel filtration and cellulose ion-exchange column chromatography. Prior to trypsin digestion, a complete acid hydrolysate was subjected to analyses for nonreducible stable and reducible intermolecular cross-links. Minute amounts of the former and significant amounts of the reduced cross-links dihydroxylysinonorleucine (1.1 mol/mol of collagen), hydroxylysinonorleucine (0.9 mol/mol of collagen), and histidinohydroxymerodesmosine (0.6 mol/mol of collagen) were found. The covalent intermolecular cross-linked two-chained peptides that were isolated were subjected to amino acid and sequence analyses. The structures for the different two-chained linked peptides were alpha 1CB4-5(76-90)[Hyl-87] X alpha 1CB6-(993-22c)[Lysald-16c], alpha 1CB4-5(76-90)[Hyl-87] X alpha 1CB6(993-22c)[Hylald-16c], alpha 2CB4(76-90)[Hyl-87] X alpha 1CB6(993-22c)[Lysald-16c], and alpha 2CB4(76-90)[Hyl-87] X alpha 1CB6(993-22c)[Hylald-16c]. The cross-link in each peptide was glycosylated. This is the first characterization by sequence analysis of a cross-link involving Hyl-87 in an alpha 2 chain in collagen. A stoichiometric conversion of residue 16c aldehyde to an intermolecular cross-link in each of the COOH-terminal nonhelical peptide regions of both alpha 1 chains in a molecule of type I collagen was found. The ratio of alpha 1 to alpha 2 intermolecularly cross-linked chains involved was 3.3:1, indicating a stereospecific three-dimensional molecular packing of type I collagen molecules in bovine periodontal ligament.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001894:Borohydrides; D002417:Cattle; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D003094:Collagen / Q000378:metabolism*; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D010513:Periodontal Ligament / Q000378:metabolism*; D014316:Tritium; D014357:Trypsin
chemical_list: D001894:Borohydrides; D046911:Macromolecular Substances; D010446:Peptide Fragments; D014316:Tritium; D003094:Collagen; D014357:Trypsin