(a) Active site of GAD65. 2F[o] – F[c] omit electron
density contoured at 1 is
also shown (atoms from Lys-PLP and GABA omitted from density
calculation). Lys-PLP moiety is shown as orange sticks;
noncovalently bound GABA molecules are colored yellow and cyan.
(b) Superposition of active site residues of GAD67 (green,
monomer A; cyan, monomer B) and GAD65 (light brown). Both Tyr434
side chain conformations from the catalytic loops of GAD67 are
shown. Tyr434 from monomer B (in cyan) enters the active site of
monomer A. In this conformation, the hydroxyl group of Tyr434 is
2.8 Å from the C atom.
(c) Interactions between catalytic loop and adjacent monomer.
Residues that are different in GAD65 are colored orange. The
alternative conformation of Tyr434 (from monomer B) is shown as
mauve bonds. Phe283 of GAD65 is shown as yellow bonds. Residues
in GAD65 corresponding to GAD67 residues 432–442 are
disordered. The PLP moiety in the active site is shown as orange
spheres, hydrogen bonds as dotted lines and water molecules as
red spheres. (d) Surface representation of active site of GAD65,
in similar orientation to that in Figure 2d. Lys396-PLP
(orange), GABA product (yellow/cyan sticks).
The above figure is reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol