ENZYME entry: EC 1.17.4.2

Accepted Name

ribonucleoside-triphosphate reductase (thioredoxin)

Alternative Name(s)

ribonucleotide reductase

Reaction catalysed

a 2'-deoxyribonucleoside 5'-triphosphate + [thioredoxin]-disulfide + H2O = a ribonucleoside 5'-triphosphate + [thioredoxin]-dithiol

Comment(s)

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-oxoacyl) 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 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.

Cross-references

Rhea expert-curated reactions

ExplorEnz

IUBMB Enzyme Nomenclature

UniProtKB/Swiss-Prot

BRENDA

MetaCyc

KEGG Ligand Database for Enzyme Nomenclature

EC2PDB

MEDLINE

All UniProtKB/Swiss-Prot entries referenced in this entry, with possibility to download in different formats, align etc.

All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 1.17.4.-
All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 1.17.-.-
All ENZYME / UniProtKB/Swiss-Prot entries corresponding to 1.-.-.-