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Figure 1.
Figure 1. Stereo views of the M. jannaschii IMPase. a, The
active site of the enzyme, with Zn2+ ions (in red) and phosphate
(yellow), superimposed with the active site model of human
IMPase (PDB code 1AWB) in complex with Ca^2+ (purple) and
inositol monophasphate (purple). There is a very good match
between the ion positions and the phosphate group. Despite the
medium resolution data, the catalytic water molecule is also
well resolved (gray and blue). b , General view of MJ0109 IMPase
(blue and green) superimposed with human IMPase (PDB code 1AWB)
(purple and red). Five loops of human IMPase do not have direct
conformational analogs (including the crucial catalytic loop) in
MJ0109. Note the significant degree of misalignment of the left
subunits despite almost perfect superposition of the active site
of the right subunits. c, Superposition of MJ0109 IMPase (blue
and green) with pig kidney FBPase (PDB code 1CNQ) (violet and
red). Only the catalytic core of the right subunit was
superimposed. The crucial catalytic loop of FBPase is encircled
by a yellow ellipsis. The active sites where
fructose-6-phosphate in blue (FBPase) and inositol-1-phosphate
in yellow (IMPase) are visualized.
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