Using the crystal structure of TEM1, we defined the distance that each interacting pair of residues is from the active site and plotted this against the conservation of the contact score (Figure ). This enabled us to identify contacts distributed throughout TEM1 that are both proximal and distant from the active site, with varying levels of conservation. Figure shows two examples of such contacting pairs in TEM1, with one example involving two pairs of variable hydrophobic residues forming hydrophobic contacts within the core. Whilst in TEM1, the residues that provide this hydrophobic interaction are Leu and Ile, we can identify the other combinations of residue pairs that form this interaction, which would require a single or double mutation to occur in TEM1.