Question

What is the difference between a site-specific endonuclease and a general endonuclease?

Answer 1

Answer. Nuclease are those enzymes that break the nucleic acid. If they break at the edges they are known as exonucleases and if break the phosphodiesterase bonds in the in between region in DNA they are known as endonucleases. They don't act specifically on any sequence in DNA, they make a simple break.

Beside these, there are one more type of endonucleases that are widely used in biotechnology experiments and these are restriction endonucleases.

The EcoRI is a restriction endonuclease extracted from E coli, recognises a specific sequence 5'GAATTC3' and its restriction site is located between G-AATTC,means it will cleave the phosphodiester bond between G and A. When EcoRI acts on dsDNA it produces two sticky ends.