ⓘ Ribonucleotide reductase

                                     

ⓘ Ribonucleotide reductase

Ribonucleotide reductase, also known as ribonucleotide diphosphate reductase, is an enzyme that catalyzes the formation of deoxyribonucleotides from ribonucleotides. It catalyzes this formation by removing the 2-hydroxyl group of the ribose ring of nucleoside diphosphates. This reduction produces deoxyribonucleotides. Deoxyribonucleotides in turn are used in the synthesis of DNA. The reaction catalyzed by RNR is strictly conserved in all living organisms. Furthermore, RNR plays a critical role in regulating the total rate of DNA synthesis so that DNA to cell mass is maintained at a constant ratio during cell division and DNA repair. A somewhat unusual feature of the RNR enzyme is that it catalyzes a reaction that proceeds via a free radical mechanism of action. The substrates for RNR are ADP, GDP, CDP and UDP. dTDP is synthesized by another enzyme from dTMP.