Figure 3.

Ribbon diagram of the catalytic subunit of Escherichia coli ATCase, E. coli OTCase, Enterococus faecalis PTCase, Xanthomonas campestris AOTCase, Bacteroidesfragilis SOTCase and E. coli YTCase. The ribbons are colored in rainbow from blue (N-terminus) to red (C-terminus). The bound substrates or inhibitors are shown in space-filling models. The 3₁ trefoil knots are formed by residues at the C-terminal end threading through the proline-rich loop (indicated by arrows) in AOTCase, SOTCase and YTCase.