title: Aging of collagen.
abstract: Current knowledge of the structure and the mechanism of formation of the covalent cross-links that fuse individual collagen molecules into a stable fiber is reviewed. Some of the mechanical properties of dermal connective tissue and the way in which these change with age can be correlated with the types of cross-link present in the tissue. Cross-links are routinely detected by treatment of a tissue sample with tritium-labeled borohydride and subsequent isolation and quantification of the cross-linked compound, which has been rendered radioactive by reaction with this reducing compound. After maturity, the number of detectable cross-links decreases even though the mechanical stability of the tissue increases. This anomaly is examined in the light of recent data suggesting that cross-links may be oxidized in vivo and thus become undetectable since they can no longer react with borohydride.
mesh_terms: D000375:Aging; D000818:Animals; D001696:Biomechanical Phenomena; D055598:Chemical Phenomena; D002621:Chemistry; D003094:Collagen; D003238:Connective Tissue / Q000032:analysis*; D006358:Hot Temperature; D006801:Humans; D012545:Schiff Bases; D012867:Skin / Q000032:analysis*
chemical_list: D012545:Schiff Bases; D003094:Collagen