STUDIES OF THE LIPIDS OF DOG SKIN .2. OBSERVATIONS OF THE LIPID METABOLISM OF PERFUSED SURVIVING DOG SKIN

[摘要] Perfusion of isolated dog skin was used for a study of the lipid metabolism of the skin. Both C14-acetate and C14-isoleucine were incorporated by the surviving skin into the lipids. With isoleucine 0.3% of the perfused radioactivity was incorporated into lipids, with acetate only 0.02%. Incorporation into all lipid fractions (fatty acids, sterols, other non-saponifiable materials) was observed. With isoleucine maximum incorporation took place in the single-branched C15 acid. The iso-branching of valine and anteiso-branching of isoleucine may serve as a skeleton in the formation of iso-and anteiso fatty acids. Otherwise, the results supported the hypothesis that in the synthesis of all fatty acids by the skin a small initial unit was elongated in a step-wise process each step of which involved the incorporation of a two-carbon unit, probably acetyl CoA. In the surviving dog skin a relatively inefficient incorporation of C14 acetate into lipids was found, possibly because the conversion of acetate into acetyl CoA was not easily performed under these experimental conditions.