Fig. 1

X-ray crystal structure of the β-lactamase from Bacillus licheniformis 749/C. The α- and α/β-domains are represented in light blue and light green, respectively. The two insertion sites 197 (located between helices 8 and 9) and 216 (inserted between helices 9 and 10) are coloured in red and are highlighted by two red arrows. The serine active site is represented by a sphere in dark blue. The numbering of the insertion sites, i.e., positions 197 and 216,  refers to the numbering scheme of class A β-lactamases [74],  which correspond to residues 168 and 187 in the sequence of the protein [74]