title: Identification of the loci of the collagen-associated Ehrlich chromogen in type I collagen confirms its role as a trivalent cross-link.
abstract: Collagenous peptides containing the Ehrlich chromogen (EC) were selectively isolated from a tryptic digest of bovine tendon by coupling to a diazotized polyacrylamide support. The isolated p-phenol-azo-EC peptides were purified and characterized by amino acid and sequence analyses. EC occurred in stoichiometric amounts in trimeric cross-linked chains originating from the known cross-link regions of type-I collagen. The major locus of the EC was alpha 2(I)Hyl-933 x alpha 1(I)Lys(Hyl)-9N x alpha 2(I)Lys(Hyl)-5N but it was also shown to occur at the loci alpha 1(I)Hyl-87 x alpha 1(I)Lys(Hyl)-16C x alpha 1(I)Lys(Hyl)-16C and alpha 1(I)Hyl-930 x alpha 1(I)Lys(Hyl)-9N x alpha 2(I)Lys(Hyl)-5N. After sequence analyses of the C-terminal helical cross-link region alpha 2(I)928-963, corrections are presented for residues 927, 930, 932 and 933 of the bovine alpha 2(I) chain. The collagen-associated EC is postulated to be a trisubstituted pyrrole formed by the reaction of the aldehyde form of a telopeptidyl lysine residue with a bifunctional keto amino cross-link. It is also proposed that when the telopeptidyl lysine residue is hydroxylated the above reaction will result in pyridinoline formation.
authors.affiliation: C.S.I.R.O. Division of Food Processing, Meat Research Laboratory, Brisbane, Queensland, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Kuypers
authors.forename: M
authors.initials: M
authors.lastname: Tyler
authors.forename: L B
authors.initials: LB
authors.lastname: Kurth
authors.forename: I D
authors.initials: ID
authors.lastname: Jenkins
authors.forename: D J
authors.initials: DJ
authors.lastname: Horgan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001391:Azo Compounds / Q000032:analysis* / Q000378:metabolism; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002863:Chromogenic Compounds / Q000032:analysis* / Q000378:metabolism; D003094:Collagen / Q000032:analysis* / Q000378:metabolism; D003432:Cross-Linking Reagents; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
chemical_list: D001391:Azo Compounds; D002863:Chromogenic Compounds; D003432:Cross-Linking Reagents; D010455:Peptides; D003094:Collagen; D014357:Trypsin