Interaction of EcoRII restriction and modification enzymes with synthetic DNA fragments. EcoRII endonuclease cleavage of substrates with repeated natural and modified recognition sites.

Interaction of EcoRII restriction endonuclease with a set of synthetic concatemer DNA duplexes with natural and modified sites for this enzyme has been studied. DNA duplexes with repeated natural sites are cleaved by EcoRII. Substitution of central AT-pair in the recognition site for a non-complementary TT-or AA-pair reduces the rate of cleavage, this effect being much more pronounced in the last case. Absence of site flanking in one strand from the 5'-terminus also results in very slow cleavage. The results obtained testify to the interaction of EcoRII with both strands of the substrate.