The effect of age on amino acid composition of human skin collagen.

To study the effect of age on amino acid composition of human skin collagen, skins from 8 women aged 0 to 93 were extracted with acetone and EDTA and then gelatinized. Gelatin was purified by extraction with chloroform-methanol and DEAE cellulose chromatography. Hydroxyproline was spectrophotometrically determined and its contents were essentially the same (12.6%). Amino acid analysis indicated no significant age-related variations in the contents of proline, hydroxyproline, lysine, and hydroxylysine over the range of 0 to 93 years of age. The content of cysteine was reasonably low (0.4 to 0.6 per 1,000 amino acid residues) except in the cases of those 0 and 93 years of age. Aldehyde content was slightly lower in young cases than in infant and old cases. These results indicate that the changes in cross-links derived from aldehyde may be responsible for the effect of age.