NgoII, a restriction endonuclease from Neisseria gonorrhoeae

Abstract

EndoR.cntdot.NgoII, a class II restriction endonuclease isolated from N. gonorrhoeae, was purified to electrophoretic homogeneity. It was separated from another restriction endonculease of N. gonorrhoeae, NgoI, by phosphocellulose chromatography. NgoII is an isochizomer of HaeIII, a restriction endonuclease of Haemophilus aegyptius, and recognized the DNA nucleotide base sequence GGCC. NgoII was able to digest phage .lambda. DNA over a wide pH range, with optimal activity at pH 8.5. The enzyme has an absolute requirement for Mg2+; maximal enzyme activity was observed at 1 mM Mg2+. The active enzyme has MW of 65,000 and appears to be composed of 6 subunits of identical MW (11,000). No methylase activity could be detected in the purified enzyme preparation.