Cross-linking and the molecular packing of corneal collagen.
We have quantitatively characterized, for the first time, the cross-linking in bovine cornea collagen as a function of age. The major iminium reducible cross-links were dehydro-hydroxylysinonorleucine (deH-HLNL) and dehydro-histidinohydroxymerodesmosine (deH-HHMD). The former rapidly diminished after birth; however, the latter persisted in mature animals at a level of 0.3 - 0.4 moles/mole of collagen. A nonreducible cross-link, histidinohydroxylysinonorleucine (HHL), previously found only in skin, was also found to be a major mature cross-link in cornea. The presence of HHL indicates that cornea fibrils have a molecular packing similar to skin collagen. However, like deH-HHMD, the HHL content in corneal fibrils only reaches a maximum value with time about half that of skin. These data suggest that the corneal fibrils are comprised of discrete filaments that are internally stabilized by HHL and deH-HHMD cross-links. This pattern of intermolecular cross-linking would facilitate the special collagen swelling property required for corneal transparency.
Yamauchi
M
M
Dental Research Center, University of North Carolina, Chapel Hill 27599-7455, USA.
Chandler
G S
GS
Tanzawa
H
H
Katz
E P
EP
D000375:Aging / Q000502:physiology*; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003094:Collagen / Q000737:chemistry* / Q000302:isolation & purification; D003315:Cornea / Q000737:chemistry* / Q000196:embryology / Q000254:growth & development; D003432:Cross-Linking Reagents; D003895:Desmosine / Q000031:analogs & derivatives / Q000032:analysis; D004151:Dipeptides / Q000032:analysis; D006639:Histidine / Q000031:analogs & derivatives / Q000032:analysis; D008961:Models, Structural; D012867:Skin / Q000737:chemistry
D003432:Cross-Linking Reagents; D004151:Dipeptides; C075793:histidinohydroxylysinonorleucine; D003895:Desmosine; D006639:Histidine; D003094:Collagen