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EC Details
EC number
Accepted name
ribonucleoside-triphosphate reductase (thioredoxin)
2′-deoxyribonucleoside 5′-triphosphate + thioredoxin disulfide + H2O = ribonucleoside 5′-triphosphate + thioredoxin
Other name(s)
ribonucleotide reductase (ambiguous), 2′-deoxyribonucleoside-triphosphate:oxidized-thioredoxin 2′-oxidoreductase
Systematic name
2′-deoxyribonucleoside-5′-triphosphate:thioredoxin-disulfide 2′-oxidoreductase
CAS registry number
The enzyme, characterized from the bacterium Lactobacillus leichmannii, is similar to class II ribonucleoside-diphosphate reductase (cf. EC 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 (α-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, ribonucleoside-triphosphate reductase (formate).
created 1972, modified 2017
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