CATH Classification

Domain Context

CATH Clusters

Superfamily Homing endonucleases
Functional Family Vitamin B12-dependent ribonucleotide reductase

Enzyme Information
Ribonucleoside-diphosphate reductase.
based on mapping to UniProt E7FHX6
2'-deoxyribonucleoside diphosphate + thioredoxin disulfide + H(2)O = ribonucleoside diphosphate + thioredoxin.
-!- This enzyme is responsible for the de novo conversion of ribonucleoside diphosphates into deoxyribonucleoside diphosphates, which are essential for DNA synthesis and repair. -!- There are three types of this enzyme differing in their cofactors. -!- Class Ia enzymes contain a diiron(III)-tyrosyl radical, class Ib enzymes contain a dimanganese-tyrosyl radical, and class II enzymes contain adenosylcobalamin. -!- In all cases the cofactors are involved in generation of a transient thiyl (sulfanyl) radical on a cysteine residue, which 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 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 and EC
Acting on ester bonds.
based on mapping to UniProt E7FHX6

UniProtKB Entries (1)

Pyrococcus furiosus DSM 3638
Vitamin B12-dependent ribonucleoside-diphosphate reductase

PDB Structure

External Links
Organism Escherichia
Primary Citation
Crystal structure of an archaeal intein-encoded homing endonuclease PI-PfuI.
Ichiyanagi, K., Ishino, Y., Ariyoshi, M., Komori, K., Morikawa, K.