IUBMB Enzyme Nomenclature


Accepted name: T4 deoxyribonuclease II

Reaction: Endonucleolytic nicking and cleavage of cytosine-containing double-stranded DNA.

Other name(s): T4 endonuclease II; EndoII (ambiguous); denA (gene name)

Comments: Requires Mg2+. This phage T4 enzyme is involved in degradation of host DNA. The enzyme primarily catalyses nicking of the bottom strand of double stranded DNA between the first and second base pair to the right of a top-strand CCGC motif. Double-stranded breaks are produced 5- to 10-fold less frequently [3]. It does not cleave the T4 native DNA, which contains 5-hydroxymethylcytosine instead of cytosine.

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Carlson, K., Krabbe, M., Nystrom, A.C. and Kosturko, L.D. DNA determinants of restriction. Bacteriophage T4 endonuclease II-dependent cleavage of plasmid DNA in vivo. J. Biol. Chem. 268 (1993) 8908-8918. [PMID: 8386173]

2. Carlson, K. and Kosturko, L.D. Endonuclease II of coliphage T4: a recombinase disguised as a restriction endonuclease. Mol. Microbiol. 27 (1998) 671-676. [PMID: 9515694]

3. Carlson, K., Kosturko, L.D. and Nystrom, A.C. Sequence-specific cleavage by bacteriophage T4 endonuclease II in vitro. Mol. Microbiol. 31 (1999) 1395-1405. [PMID: 10200960]

4. Andersson, C.E., Lagerback, P. and Carlson, K. Structure of bacteriophage T4 endonuclease II mutant E118A, a tetrameric GIY-YIG enzyme. J. Mol. Biol. 397 (2010) 1003-1016. [PMID: 20156453]

[EC created 2014]

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