KEGG   ENZYME: 1.17.4.2Help
Entry
EC 1.17.4.2                 Enzyme                                 

Name
ribonucleoside-triphosphate reductase (thioredoxin);
ribonucleotide reductase (ambiguous);
2'-deoxyribonucleoside-triphosphate:oxidized-thioredoxin 2'-oxidoreductase
Class
Oxidoreductases;
Acting on CH or CH2 groups;
With a disulfide as acceptor
BRITE hierarchy
Sysname
2'-deoxyribonucleoside-5'-triphosphate:thioredoxin-disulfide 2'-oxidoreductase
Reaction(IUBMB)
2'-deoxyribonucleoside 5'-triphosphate + thioredoxin disulfide + H2O = ribonucleoside 5'-triphosphate + thioredoxin [RN:R04315]
Reaction(KEGG)
Substrate
2'-deoxyribonucleoside 5'-triphosphate [CPD:C00677];
thioredoxin disulfide [CPD:C00343];
H2O [CPD:C00001]
Product
ribonucleoside 5'-triphosphate [CPD:C03802];
thioredoxin [CPD:C00342]
Comment
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).
History
EC 1.17.4.2 created 1972, modified 2017
Pathway
Purine metabolism
Pyrimidine metabolism
Metabolic pathways
Orthology
K00527  
ribonucleoside-triphosphate reductase (thioredoxin)
Genes
PPQ: 
LAC: 
LAI: 
LAD: 
LAF: 
SD55_0041(nrdJ)
LDB: 
Ldb0096(rtpR)
LBU: 
LDE: 
LDL: 
LBR: 
LBK: 
LCA: 
LPQ: 
LPI: 
LPAP: 
LCB: 
LCZ: 
LCS: 
LCE: 
LCW: 
LCL: 
LCX: 
LGA: 
LRU: 
LHE: 
LHL: 
LHR: 
LHV: 
lhe_0057(rtpR)
LHH: 
LHD: 
LRH: 
LGG_02296(rtpR)
LRG: 
LRL: 
LRA: 
LRHK_2294(nrdJ)
LRO: 
LRC: 
LAM: 
LAY: 
LBH: 
LBN: 
LKE: 
LAW: 
LAE: 
LGN: 
LKO: 
LHI: 
LGL: 
LPAR: 
LPD: 
LAMY: 
MARR: 
AEY: 
FLM: 
 » show all
Taxonomy
Reference
1  [PMID:14299643]
  Authors
BLAKLEY RL.
  Title
COBAMIDES AND RIBONUCLEOTIDE REDUCTION. I. COBAMIDE STIMULATION OF RIBONUCLEOTIDE REDUCTION IN EXTRACTS OF LACTOBACILLUS LEICHMANNII.
  Journal
J. Biol. Chem. 240 (1965) 2173-80.
Reference
2  [PMID:5924645]
  Authors
Goulian M, Beck WS.
  Title
Purification and properties of cobamide-dependent ribonucleotide reductase from Lactobacillus leichmannii.
  Journal
J. Biol. Chem. 241 (1966) 4233-42.
Reference
3  [PMID:7014560]
  Authors
Stubbe J, Ackles D, Segal R, Blakley RL
  Title
On the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii. Evidence for 3' C--H bond cleavage.
  Journal
J. Biol. Chem. 256 (1981) 4843-6.
Reference
4  [PMID:3512563]
  Authors
Ashley GW, Harris G, Stubbe J
  Title
The mechanism of Lactobacillus leichmannii ribonucleotide reductase. Evidence for 3' carbon-hydrogen bond cleavage and a unique role for coenzyme B12.
  Journal
J. Biol. Chem. 261 (1986) 3958-64.
Reference
5  [PMID:9818192]
  Authors
Lawrence CC, Stubbe J
  Title
The function of adenosylcobalamin in the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii.
  Journal
Curr. Opin. Chem. Biol. 2 (1998) 650-5.
Reference
6  [PMID:9930982]
  Authors
Licht SS, Booker S, Stubbe J
  Title
Studies on the catalysis of carbon-cobalt bond homolysis by ribonucleoside triphosphate reductase: evidence for concerted carbon-cobalt bond homolysis and thiyl radical formation.
  Journal
Biochemistry. 38 (1999) 1221-33.
Other DBs
ExplorEnz - The Enzyme Database: 
IUBMB Enzyme Nomenclature: 
ExPASy - ENZYME nomenclature database: 
BRENDA, the Enzyme Database: 
CAS: 
9068-66-0

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