Endonuclease

An endonuclease is a nuclease that degrades a substrate (the nucleic acid - DNA and / or RNA ) by cleaving an internal phosphodiester bond, i.e. does not cleave it at the end. This also means that, in contrast to exonucleases, the reaction products are not a single nucleotide , but rather multiple nucleotides .

Successive reactions result in ever shorter fragments until they are too short to serve as a substrate for the endonuclease or until there are no longer any recognition sites. This so-called endonucleolytic digestion leaves behind two fragments per reaction, while exonucleolytic digestion results in a shortened nucleic acid molecule and a nucleic acid monomer through an exonuclease .

The endonucleases include e.g. B. the restriction enzymes and the homing endonucleases . Restriction enzymes are used in restriction digestion .

In the course of genome editing , endonucleases with a recognizable recognition sequence are used, e.g. B. Transcription Activator-like Effector Nucleases , the CRISPR / Cas method and zinc finger nucleases .

See also

• Exoribonuclease (RNA)
• Deoxyribonuclease (DNA)

literature

• Jeremy M. Berg , John L. Tymoczko , Lubert Stryer : Stryer Biochemistry . 6th edition, Spektrum Akademischer Verlag, Munich 2007. ISBN 978-3-8274-1800-5 .
• Cornel Mülhardt: The Experimenter: Molecular Biology / Genomics. Sixth edition. Spectrum Akademischer Verlag, Heidelberg 2008. ISBN 3-8274-2036-9 .