Mammalian ribonucleotide reductase is a complex enzyme modified in its activity by a complex regulatory system involving adenosine triphosphate (ATP) and deoxyribonucleoside triphosphates. Infection of KB cells with herpes simplex virus (HSV) type 1 or 2 induces the formation of an altered ribonucleotide reductase. The properties of partially purified reductase from uninfected KB cells have bee...

The E. coli ribonucleotide reductase (RNR), a paradigm for class Ia enzymes including human RNR, catalyzes the biosynthesis of DNA building blocks and requires di-iron tyrosyl radical (Y122.) cofactor activity. knowledge on in vitro Y122. structure its distribution within β2 subunit has accumulated over years; yet little information exists vivo Y122.. Here, we characterize this essential whole ...

Ribonucleotide reductase (RR) is a multisubunit enzyme responsible for the reduction of ribonucleotides to their corresponding deoxyribonucleotides, which are building blocks for DNA replication and repair. The key role of RR in DNA synthesis and cell growth control has made it an important target for anticancer therapy. Increased RR activity has been associated with malignant transformation an...

possible cancer chemotherapeutic agents. Howeven, pre himinary data indicate that these compounds are toxic and are not effective in humans (4, 14). In order to develop an effective chemothemapeutic agent for which the mode of action is inhibition of nibonucleotide meductase activity, a number of ahiphatic and aromatic hydroxamic acids and their corresponding amides and esters were synthesized ...

Cullin4, Ddb1 and Cdt2 are core subunits of the ubiquitin ligase complex CRL4(Cdt2), which controls genome stability by targeting Spd1 for degradation during DNA replication and repair in fission yeast. Spd1 has an inhibitory effect on ribonucleotide reductase (RNR), the activity of which is required for deoxynucleotide (dNTP) synthesis. The failure to degrade Spd1 in mutants where CRL4(Cdt2) i...

Ribonucleotide reductase, which is composed of the two protein components R1 and R2, is a highly regulated enzyme activity that is essential for DNA synthesis and repair. Recent studies have shown that elevated expression of the rate-limiting R2 component increases Raf-1 protein activation and mitogen-activated protein kinase activity and acts as a novel malignancy determinant in cooperation wi...

The structural requirements for reactivity at the substrate site and for interaction at the regulatory site of ribonucleotide reductase from Lacfobacillus leichmannii have been studied with the use of several nucleotide antibiotics. The 5’4riphosphates of tubercidin, toyocamycin, and sangivamycin were substrates. Without Mg++, tubercidin 5’triphosphate was a better substrate than ATP. Therefore...

Ribonucleotide reductase (EC 1.17.4.1 -2) catalyses the direct reduction of ribonucleotides to the corresponding deoxyribonucleotides. This reaction enabled the evolution from the early ‘RNA world’ to the present ‘DNA world’. Storage of genetic information as DNA instead of RNA is much more stable and this was a prerequisite for the later development of multiple, separate, species [l] . Ribonuc...