Ribonucleotide Reductase (RNR) plays a critical role in DNA synthesis, and is a well-recognized target for cancer chemotherapeutic and antiviral agents. RNR inhibition precludes DNA transcription and repair, from which results cell apoptosis. Many regulation checkpoints concerning RNR activity have been unravelled through the last two decades, with potential use to inhibit enzyme activity. This...

F-box proteins are the substrate binding subunits of SCF (Skp1-Cul1-F-box protein) ubiquitin ligase complexes. Using affinity purifications and mass spectrometry, we identified RRM2 (the ribonucleotide reductase family member 2) as an interactor of the F-box protein cyclin F. Ribonucleotide reductase (RNR) catalyzes the conversion of ribonucleotides to deoxyribonucleotides (dNTPs), which are ne...

Ribonucleotide reductase catalyses the reaction that eventually provides the four deoxyribonucleotides required for the synthesis and repair of DNA. U.v.-cross-linking and band-shift experiments have identified in COS 7 monkey cells an approx. 57 kDa ribonucleotide reductase RI mRNA-binding protein called RlBP, which binds specifically to a 49-nt region of the RI mRNA 3'-untranslated region (3'...

Ribonucleotide reductase maintains cellular deoxyribonucleotide pools and is thus tightly regulated during the cell cycle to ensure high fidelity in DNA replication. The Sml1 protein inhibits ribonucleotide reductase activity by binding to the R1 subunit. At the completion of each turnover cycle, the active site of R1 becomes oxidized and subsequently regenerated by a cysteine pair (CX2C) at it...

The ribonucleotide reductase gene tandem bnrdE/bnrdF in SPbeta-related prophages of different Bacillus spp. isolates presents different configurations of intervening sequences, comprising one to three of six non-homologous splicing elements. Insertion sites of group I introns and intein DNA are clustered in three relatively short segments encoding functionally important domains of the ribonucle...

Ribonucleotide reductase M2 subunit (RRM2) is one of the two subunits of human ribonucleotide reductase which plays a critical role in tumor progression. The aim of the present study was to analyze its expression, clinical significance and biological functions in gastric adenocarcinoma. We observed the upregulation of RRM2 mRNA and protein in all nine gastric cancer cell lines examined. In pair...

Ribonucleotide reductase activity in cell-free tissue extracts from Yaba monkey tumors, spleen, kidney, liver, and muscle has been measured in vitro. The specific activity of the enzyme in the Yaba tumor extracts was approximately two times that observed in normal muscle tissue extracts and ten times that in normal liver, spleen and kidney extracts. The specific activity in Yaba tumor extracts ...

Infection o f Chlorella-like green algae with freshwater phycoviruses is associated with a large and rapid de­ mand for D N A precursors which cannot be met by the algal deoxyribonucleotide-synthesizing enzymes. We have demonstrated in these cells an up to ten-fold in­ crease o f the key enzyme, ribonucleotide reductase, 1 —2 h post infection. The enzyme activity has been par­ tially enriched f...

A 5’-deoxyadenosylcobalamin-agarose adsorbent has been prepared for the purification by affinity chromatography of enzymes which require 5’-deoxyadenosylcobalamin as a coenzyme. The synthesis involved the covalent attachment of cyanocobalamin to agarose through a 12 carbon chain. This hydrocarbon chain was attached to the corrin nucleus by reacting diaminododecane with cyanocobalamin e-carboxyl...