AGE-RELATED-CHANGES IN THE REDUCIBLE CROSS-LINKS OF CONNECTIN FROM HUMAN SKELETAL-MUSCLE

After NaB3H4-reduction of connectin from human skeletal muscle, the changes in the amounts of the reducible cross-links and specific radioactivity of this elastic protein were followed throughout the whole life-span from embryo to old age. The reducible cross-links, aldimine forms of lysinonorleucine and histidino-hydroxymerodesmosine, and unidentified reducible compounds, which were assumed to be cross-linking amino acids, were found to remarkably decrease with age. A progressive decrease in the incorporation of tritium into the reducible compounds was also observed. We conclude that the conversion of the reducible cross-links derived from lysine and hydroxylysine aldehydes to non-reducible compounds is an essential step in the maturation of connectin fibrils, similar to collagen fibrils. © 1979.