FIG. 3.

Aligned sequences of the CDs of Cel9G of C. cellulolyticum, CelE4 of T. fusca, and Cel9D of C. thermocellum. The representative secondary structures are color coordinated with the sequence names. The putative catalytic base (Asp-55) and the proton donor (Glu-420) are represented by black stars under the sequences, and black triangles denote conserved aromatic residues involved in substrate stacking (see the text for an explanation of residue 208). The sequences were aligned with the CLUSTALW program (45), and the figure was prepared by using ESPript (16).