EC - Deoxyribonuclease IV

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IntEnz Enzyme Nomenclature


Accepted name:
deoxyribonuclease IV
Other names:
E. coli endonuclease IV
Escherichia coli endonuclease II
deoxriboendonuclease [misleading]
endodeoxyribonuclease [misleading]
endodeoxyribonuclease IV (phage T4-induced) [misleading]
endonuclease II
endodeoxyribonuclease IV (phage T4-induced) [misleading]
endonuclease IV
deoxyribonuclease IV (phage T4-induced) [misleading]
nfo (gene name)
Systematic name:



The enzyme is an apurinic/apyrimidinic (AP) site endonuclease that primes DNA repair synthesis at AP sites. It specifically cleaves the DNA backbone at AP sites and also removes 3' DNA-blocking groups such as 3' phosphates, 3' phosphoglycolates, and 3' α,β-unsaturated aldehydes that arise from oxidative base damage and the activity of combined glycosylase/lyase enzymes. It is also the only known repair enzyme that is able to cleave the DNA backbone 5' of the oxidative lesion α-deoxyadenosine. The enzyme has a strong preference for single-stranded DNA. Formerly EC

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00599
Structural data: CSA , EC2PDB
Gene Ontology: GO:0008833
CAS Registry Number: 37211-67-9 (not distinguished from EC
UniProtKB/Swiss-Prot: (271) [show] [UniProt]


  1. Friedberg, E.C. and Goldthwait, D.A.
    Endonuclease II of E. coli. I. Isolation and purification.
    Proc. Natl. Acad. Sci. USA 62: 934-940 (1969). [PMID: 4895219]
  2. Friedberg, E.C., Hadi, S.-M. and Goldthwait, D.A.
    Endonuclease II of Escherichia coli. II. Enzyme properties and studies on the degradation of alkylated and native deoxyribonucleic acid.
    J. Biol. Chem. 244: 5879-5889 (1969). [PMID: 4981786]
  3. Hadi, S.M. and Goldthwait, D.A.
    Endonuclease II of Escherichia coli. Degradation of partially depurinated deoxyribonucleic acid.
    Biochemistry 10: 4986-4993 (1971). [PMID: 4944066]
  4. Cunningham, R. P., Saporito, S. M., Spitzer, S. G., Weiss, B.
    Endonuclease IV (nfo) mutant of Escherichia coli.
    J. Bacteriol. 168: 1120-1127 (1986). [PMID: 2430946]
  5. Ide, H., Tedzuka, K., Shimzu, H., Kimura, Y., Purmal, A. A., Wallace, S. S., Kow, Y. W.
    Alpha-deoxyadenosine, a major anoxic radiolysis product of adenine in DNA, is a substrate for Escherichia coli endonuclease IV.
    Biochemistry 33: 7842-7847 (1994). [PMID: 7516707]
  6. Hosfield, D. J., Guan, Y., Haas, B. J., Cunningham, R. P., Tainer, J. A.
    Structure of the DNA repair enzyme endonuclease IV and its DNA complex: double-nucleotide flipping at abasic sites and three-metal-ion catalysis.
    Cell 98: 397-408 (1999). [PMID: 10458614]

[EC created 1972 as EC, transferred 1978 to EC, modified 2014]