Enzyme systems containing a single subunit and requiring only magnesium for endonucleolytic activity. The corresponding modification methylases are separate enzymes. The systems recognize specific short DNA sequences and cleave either within, or at a short specific distance from, the recognition sequence to give specific double-stranded fragments with terminal 5'-phosphates. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 3.1.21.4.

Synonyms: DNA Restriction Enzymes, Type II, Type II Restriction Enzymes, Deoxyribonucleases, Type II, Site Specific, Type II Site Specific Deoxyribonucleases, Deoxyribonucleases, Type II Site Specific, DNase, Site Specific, Type II, Deoxyribonucleases, Type II, Site-Specific, Site-Specific DNase, Type II, Site Specific DNase, Type II, Type II Site-Specific DNase, Type II Site-Specific Deoxyribonucleases, Type II Site Specific DNase, DNase, Site-Specific, Type II, EC 3.1.21.4, Deoxyribonucleases, Type II Site-Specific, Restriction Endonucleases, Type II