Endonuclease

A nuclease is referred to as an endonuclease that degrades a substrate ( DNA and / or RNA) by cleavage of an internal phosphodiester bond, so does not cleave terminal. This also means that, in contrast to the reaction products exonucleases no single nucleotide, but always Mehrfachnukleotide arise.

By successive reactions occur more shorter fragments, until they are too short to serve as a substrate or the endonuclease recognition sites are no longer available. This so-called endonucleolytic digestion leaves per reaction two fragments, whereas in the exonucleolytic digestion by an exonuclease a truncated nucleic acid molecule and a nucleic acid monomer is formed.

To include the endonucleases such as restriction enzymes and the homing endonucleases.