Independent Biosynthesis of Different Hemin Chromoproteins- Cytochrome c in Various Tissues.

Abstract

Studies in rats with glycine-2-C14 administered intraperit. to intact and partially hepatectomized animals demonstrated the participation of glycine in the biosynthesis of cytochrome c. The incorporation of C14 from glycine-2-C14 was of relatively very low order in the cytochrome c of heart and very high order in liver tissue which had undergone active regeneration, following partial hepatectomy. In descending order of magnitude, characteristic levels of radioactivity were found in regenerating liver, control liver, kidney, skeletal muscle and heart. The incorporation of C14 in cytochrome "c" of regenerating liver tissue was some 15-fold greater than in Hb. A provisional rate of "turnover" for liver cytochrome "c" was calculated from the difference in C14 activity at 6 and 11 days of regeneration. This proved to be appreciably higher (12- to 15-fold) than the normal rate of Hb turnover. Despite the chemical identity of the hemin moiety, it is tentatively proposed that chromoprotein biosynthesis is a general property of living, aerobic cells, and not confined to a single, specialized tissue.