Incorporation and Conversion of Lysine-2-C 14 in Rat Biopsy-Connective Tissue

Summary

1. C¹⁴-labeled lysine administered intraperitoneally into the rat is incorporated within hours into the saline-soluble and -insoluble non-collagenous protein and collagen of biopsy-connective tissue. Radioactivity is confined to lysine in all fractions of connective tissue except for a portion which is converted to hydroxylysine in the collagen. 2. Following appearance of radioactivity in all fractions of connective tissue, decay occurs rapidly in saline-insoluble non-collagenous protein and saline-soluble protein and slowly in the collagen fraction. Thirty days after injection of labeled lysine approximately 10% of maximum activity remained in the saline protein fractions while 30% remained in collagen. 3. Incorporation of labeled lysine into the non-collagenous protein of connective tissue is not influenced by tissue age while its incorporation into the collagen appears to decrease with tissue age. 4. Specific activity of labeled hydroxylysine from a 300-day old tissue of a female rat was approximately twice that of a comparably aged tissue from a male rat.