To illustrate this and further capabilities of KIN, we used this tool to find shared interaction networks among 69 structures of class A β-lactamases. We projected these interaction networks onto the structure of TEM-1 (PDB ID: 1M40 ( )) as a representative system throughout, as this enzyme is commonly associated with clinical ß-lactam resistance in Gram-negative bacteria and is considered a model class A β-lactamase . The most conserved interactions among β-lactamases (Figure ) comprise hydrogen bonding networks within secondary structural elements and highly preserved hydrophobic core interactions. Interactions can also be filtered by whether the side chain or main chain is involved, and filters can be applied consecutively to focus on a specific set of interactions more deeply (Figure ). Users can also obtain the set of interactions conserved within the analyzed family but not present in the protein of interest (Figure ). This is designed to help understand why a particular protein differs functionally from the rest of an evolutionary group or potentially to guide protein engineering.