DNA/RNA non-specific endonuclease

{{Infobox protein family

| Symbol = Endonuclease_NS

| Name = Endonuclease_NS

| image = PDB 1smn EBI.jpg

| width =

| caption = identification of the serratia endonuclease dimer: structural basis and implications for catalysis

| Pfam = PF01223

| Pfam_clan = CL0263

| InterPro = IPR001604

| SMART =

| PROSITE = PDOC00821

| MEROPS =

| SCOP = 1smn

| TCDB =

| OPM family =

| OPM protein =

| CAZy =

| CDD = cd00091

}}

In molecular biology, enzymes in the DNA/RNA non-specific endonuclease family of bacterial and eukaryotic endonucleases {{EC number|3.1.30.-}} share the following characteristics: they act on both DNA and RNA, cleave double-stranded and single-stranded nucleic acids and require a divalent ion such as magnesium for their activity. A histidine has been shown to be essential for the activity of the Serratia marcescens nuclease. This residue is located in a conserved region which also contains an aspartic acid residue that could be implicated in the binding of the divalent ion.{{cite journal |vauthors=Friedhoff P, Gimadutdinow O, Pingoud A | title = Identification of catalytically relevant amino acids of the extracellular Serratia marcescens endonuclease by alignment-guided mutagenesis | journal = Nucleic Acids Res. | volume = 22 | issue = 16 | pages = 3280–7 |date=August 1994 | pmid = 8078761 | pmc = 523719 | doi = 10.1093/nar/22.16.3280}}

Notable members of the family include Serratia marcescens NucA and human Exonuclease G.