Dermal Urea-Soluble Collagen ∗

Summary

We estimated the yield and cross-linking of dermal urea soluble collagen as it relates to the process of aging. Twenty skin specimens, ranging in age from a 6-month-fetus to a 70-year-old man were successively extracted with 1 M NaCl, 0.1 M citrate buffer, pH 3.8, and 6M urea, pH 7.0 Distribution of alpha and beta chains, without previous heat denaturation was studied by acrylamide gel electrophoresis. The yield was as follows: fetuses 63-116 mg/gm (dry wt. dermis); 8 to above 60 years, 16-41 mg/gm. There was about 40% alpha and 60% beta chains. The alpha:beta ratio was 0.64 ± 0.14 for all specimens. In the alpha region, 3 distinct bands were noted suggesting a third subunit. Urea-soluble collagen represents a larger and more cross-linked fraction than the salt and acid soluble collagens and decreases with aging.