MOLECULAR MECHANISMS OF LIVER REGENERATION .7. CONVERSION OF CYTIDINE TO DEOXYCYTIDINE IN RAT REGENERATING LIVERS

Ribonucleotide reductase activity was measured in a high speed supernatant fraction of regenerating rat liver. The activity of the enzyme varied with the concentrations of ATP in the reaction mixture at pH 8.O. While no enzyme activity could be demonstrated in normal liver, the activity of the reductase was well developed at 24 hr after hepatectomy, and further increased between 24 and 36 hr after operation. Inasmuch as whole body irradiation and the injection of actinomycin D interferes with the development of reductase activity in regenerating liver, it is proposed that ribonucleotide reductase is formed de novo in regenerating rat liver. © 1969.