Figure 1.

Catalytic residues of OtCE15A and other CE15 members. Comparison of the catalytic triads of OtCE15A (PDB code 6GS0; A), TtCE15A from T. turnerae (PDB code 6HSW; B), and StGE2 from Thermothelomyces thermophila (previously Sporotrichum thermophile; PDB code 4G4G; C) shows alternate positions of the catalytic acid residue in TtCE15A and StGE2, whereas an acidic residue is present in both locations in OtCE15A. The methyl ester of 4-O-methyl glucuronoate determined in the structure of StGE2 (PDB code 4G4J) is shown in green sticks from structural alignment of the CE15 proteins.