The metallo-ß-lactamases use a metal ion to catalyze the hydrolysis of the ß-lactam bond in ß-lactam antibiotics. They fall into two families: Class ß and Class ß. The current Ambler classification combines these two families into a single Class, Class B, and classifies Class B as Subclasses B1 and B3, while classifying Class E as Subclass B3.

At the amino acid sequence level there is homology within each class, but no detectable homology between classes. At the structural level there is homology between the classes.

Click the buttons in the navigation bar at the left to access pages for the Metallo Structural phylogeny, the Class B phylogeny and the Class E phylogeny.