IUBMB Enzyme Nomenclature


Accepted name: type III site-specific deoxyribonuclease

Reaction: Endonucleolytic cleavage of DNA to give specific double-stranded fragments with terminal 5'-phosphates

Other name(s): type III restriction enzyme; restriction-modification system

Comments: This is a large group of enzymes which, together with those now listed as EC (type 1 site-specific deoxyribonuclease) and EC (type II site-specific deoxyribonuclease), were previously listed separately in sub-subclasses EC 3.1.23 and EC 3.1.24. They have an absolute requirement for ATP but do not hydrolyse it; S-adenosy-L-methionine stimulates the reaction, but is not absolutely required. They recognize specific, short DNA sequences and cleave a short distance away from the recognition sequence. These enzymes exist as complexes with enzymes of similar specificity listed under EC [site-specific DNA-methyltransferase (adenine-specific)] or EC [site-specific DNA-methyltransferase (cytosine-specific)]. A complete listing of all of these enzymes has been produced by R.J. Roberts and is available at http://rebase.neb.com/rebase/rebase.html

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 9075-08-5 (not distinguished from EC


1. Roberts, R.J. Restriction enzymes and their isoschizomers. Nucleic Acids Res. 18 (1990) 2331-2365. [PMID: 2159140]

[EC created 1984 from EC 3.1.23 and EC 3.1.24]

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