From Biology-Online Dictionary | Biology-Online Dictionary


noun, plural:exonucleases

A nuclease that catalyzes the hydrolysis of phosphodiester bond, cleaving a single nucleotide from the end of a polynucleotide chain.


The enzyme may occur as individual enzyme or as part of a larger enzyme complex. For instance, DNA polymerase I has 3' to 5' exonuclease activity which is used in editing and proofreading DNA for errors.

Word origin: Greek éxō (outside) + nuclease.

Compare: endonuclease
See also: proofreading