Figure 4.
(A) Stereo figure depicting the active site of KPC-2 with bicine and a superpositioned cephalosporin. Bicine (thick dark sticks) and the cephalosporin cephalothin (thin dark sticks) are depicted. The position of cephalothin was obtained by superimposing the AmpC:cephalothin substrate complex (PDBid 1KVL (32)) with KPC-2. The Cα atoms used in the superpositioning are KPC-2 residues 69-73, 132, and 235-238 onto AmpC residues 63-67, 152, and 316-319 (superposition resulted in an r.m.s.d. of 0.67Å for the 10 Cα atoms). Hydrogen bonds with bicine are shown as dashed lines. The carbon position of cephalothin in which cefoxitin has a 7α-OCH3 substituent is labeled with a ‘7’. (B) Schematic diagram of interactions of bicine in the active site of KPC-2. Hydrogen bonds are depicted by dashed lines; van der Waals interactions with W105 are shown by a curved line with perpendicular lines. Hydrogen bond distances are listed in Å.