Figure 4. Structural comparison of the conserved ββα-metal fold and catalytic sites of Gme HNHE, Hpy99I, phage T4 endonuclease VII, periplasmic nuclease Vvn from Vibrio vulnificus, and endonuclease I from bacterium Vibrio salmonicida.
Some additional secondary structures (β sheets) were inserted in the ββα-Me fold in Vvn nuclease and endonuclease I.