|
Figure 2.
Figure 2. (a) The active center structure of the
CelK-cellobiose complex. Side-chains of the active site residues
are shown in orange. The red sphere is the cadmium ion found at
the catalytic site. Hydrogen bonds are shown in yellow. The
cellobiose molecule is shown in green. F[o] -F[c] electron
density map is superimposed to the model (contoured at 2.5s
level, the atoms of cellobiose were excluded from the phase
calculation). (b) The active center and carbohydrate ligand
structures of CelK and Cel5A in different ligand states. Only
the main-chain atoms are presented for the loops Ala233-Gly239
of Cel5A and Gln490-Gly495 of CelK. The bound sugars are labeled
according to the binding sites. Hydrogen bonds are shown in
yellow. The superimposed structures are Cel5A without ligand
(open conformation, green), complexed with cellobiose (open
conformation, blue) and covalent-intermediate (closed
conformation, gray) and CelK without ligand (closed
conformation, red) and cellobiose complex (closed conformation,
orange).
|
