Elimination of non-specific nucleases from restriction endonuclease preparations by different binding on free DNA ligand.

In the purification of a novel restriction endonuclease (an AvaIII isoschizomer, isolated in this laboratory) standard methods were insufficient to eliminate non-specific nuclease contaminations. Taking advantage of the specific site recognition and binding of the restriction endonuclease on DNAs, a method is described for the simple extraction of non-specific nucleases. DNA substrates without recognizable sites do not bind the restriction endonuclease, while non-specific nucleases are absorbed to, and eliminated with, the DNA via gel filtration chromatography under special conditions.