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Information on EC 1.17.4.2 - ribonucleoside-triphosphate reductase (thioredoxin)

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IUBMB Comments
The enzyme, characterized from the bacterium Lactobacillus leichmannii, is similar to class II ribonucleoside-diphosphate reductase (cf. EC 1.17.4.1). However, it is specific for the triphosphate versions of its substrates. The enzyme contains an adenosylcobalamin cofactor that is involved in generation of a transient thiyl (sulfanyl) radical on a cysteine residue. This radical attacks the substrate, forming a ribonucleotide 3'-radical, followed by water loss to form a ketyl (alpha-oxoalkyl) radical. The ketyl radical is reduced to 3'-keto-deoxynucleotide concomitant with formation of a disulfide anion radical between two cysteine residues. A proton-coupled electron-transfer from the disulfide radical to the substrate generates a 3'-deoxynucleotide radical, and the final product is formed when the hydrogen atom that was initially removed from the 3'-position of the nucleotide by the thiyl radical is returned to the same position. The disulfide bridge is reduced by the action of thioredoxin. cf. EC 1.1.98.6, ribonucleoside-triphosphate reductase (formate).
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The enzyme appears in viruses and cellular organisms
Synonyms
2'-deoxyribonucleoside-triphosphate:oxidized-thioredoxin 2'-oxidoreductase, adenosylcobalamin-dependent ribonucleoside-triphosphate reductase, class Ib ribonucleotide reductase, class Ib RNR, class II ribonucleotide reductase, class II RNR, class III ribonucleotide reductase, class III RNR, More, nrdD, more
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
2'-deoxyribonucleoside 5'-triphosphate + thioredoxin disulfide + H2O = ribonucleoside 5'-triphosphate + thioredoxin
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requires a cobamide coenzyme and ATP
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PATHWAY SOURCE
PATHWAYS
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