Figure 1.
Figure 1. A schematic diagram of the GPb dimeric molecule
viewed down the molecular dyad. One subunit is colored in dark
green and the other in light green. The position is shown for
the catalytic site. The catalytic site, marked by glucose (GLC)
and the essential cofactor pyridoxal 5 -phosphate
(PLP), shown in ball-and-stick representations, is buried at the
center of the subunit and is accessible to the bulk solvent
through a 15-Å long channel. Close-up: Details of the
interactions of glucose with residues of the catalytic site.
-D-Glucose,
a competitive inhibitor (K[i] = 1.7 mM), on binding at the
catalytic site, promotes the less active T state through
stabilization of the closed position of the 280s loop (shown in
cream) which blocks access for the substrate (glycogen) to the
catalytic site. In particular, the -1-OH
is hydrogen-bonded to Asp283 (OD1), through a water molecule,
and the 2-OH is hydrogen-bonded directly to Asn284 (ND2).
-phosphate
(PLP), shown in ball-and-stick representations, is buried at the
center of the subunit and is accessible to the bulk solvent
through a 15-Å long channel. Close-up: Details of the
interactions of glucose with residues of the catalytic site.
-D-Glucose,
a competitive inhibitor (K[i] = 1.7 mM), on binding at the
catalytic site, promotes the less active T state through
stabilization of the closed position of the 280s loop (shown in
cream) which blocks access for the substrate (glycogen) to the
catalytic site. In particular, the