Endonuclease IV, cloned from the E. coli nfo gene, is a metalloenzyme
that functions in vivo to repair free-radical damage in DNA.1 The
enzyme has Class II abasic endonuclease activity, which has utility in many
areas of DNA damage and repair research.1 The enzyme can also act
as an 3´ diesterase. Endonuclease IV is useful in the study of the effects
of antitumor drugs such as bleomycin on nucleic acids in vivo.2
Unit Definition: One unit of Endonuclease IV will relax 1 µg
of partially depurinated, covalently closed supercoiled plasmid DNA in 30 minutes
at 37°C under standard assay conditions.
Storage Buffer: 50% glycerol containing 50 mM Tris-HCl (pH 7.5), 0.1
M NaCl, 1 mM DTT, and 0.1% Triton® X-100.
Quality Control: Endonuclease IV is tested in degradation of dsDNA
and is free of detectable RNase and double-stranded exonuclease activities.