Dietary Composition and Tissue Protein Synthesis

Skin collagen synthesis as measured by the uptake of radioglycine was considerably decreased in rats fed amino acid-deficient diets. Excess dietary tryptophan (1.5% added to a 12% casein diet) had a similar although less marked effect. The composition of skin with respect to its water, fat, collagen and fat-free total solids was shown to be greatly dependent upon the nature of the diet. The total amount of collagen synthesized as a response to the subcutaneous implantation of polyvinyl sponges was slightly decreased by the consumption of diets inadequate for optimal growth. Serum glutamic-oxaloacetic transaminase was increased in the animals fed amino acid-deficient diets, whereas liver arginase activity seemed to reflect the quantity of protein ingested rather than its amino acid composition.