Definition for Endonuclease
From Biology Forums Dictionary
Endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain, such as DNA. Endonucleases that are non-specific, such as Deoxyribonuclease I, cut DNA relatively without regard to sequence, while many, typically called restriction endonucleases or restriction enzymes, cleave only at very specific nucleotide sequences. Endonucleases differ from exonucleases, which cleave the ends of recognition sequences instead of the middle (endo) portion.