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ENZYME

ENZYME entry: EC 1.17.4.2

Accepted Name
ribonucleoside-triphosphate reductase (thioredoxin)
Alternative Name(s)
ribonucleotide reductase
Reaction catalysed
[thioredoxin]-disulfide + a 2'-deoxyribonucleoside 5'-triphosphate + H2O <=> [thioredoxin]-dithiol + a ribonucleoside 5'-triphosphate
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
BRENDA1.17.4.2
EC2PDB1.17.4.2
ExplorEnz1.17.4.2
PRIAM enzyme-specific profiles1.17.4.2
KEGG Ligand Database for Enzyme Nomenclature1.17.4.2
IUBMB Enzyme Nomenclature1.17.4.2
IntEnz1.17.4.2
MEDLINEFind literature relating to 1.17.4.2
MetaCyc1.17.4.2
Rhea expert-curated reactions1.17.4.2
UniProtKB/Swiss-Prot
Q54CW7, RTPR_DICDIQ2PDF6, RTPR_EUGGRQ5FMX8, RTPR_LACAC
Q1G7W2, RTPR_LACDAQ04CQ7, RTPR_LACDBQ041L3, RTPR_LACGA
A8YW74, RTPR_LACH4Q59490, RTPR_LACLEQ035U1, RTPR_LACP3
Q03PB4, RTPR_LEVBAA6Q367, RTPR_NITSBQ857H2, VG50_BPMB2
O64240, VG50_BPMD2Q05262, VG50_BPML5

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