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Figure 3.
FIG. 3. NADP+ and 15-oxo-PGE[2] binding to LTB[4]
12-HD/PGR. A, a stereo view of the bound NADP+ in the binary
complex structure. The|F[o]| -|F[c]| simulated annealing omit
electron density map is contoured at 3.0  (orange) and 6.0 (cyan).
The carbon atoms of NADP+ are yellow, and those of side chains
involved in NADP+ binding are green. Single-letter codes are
used for amino acid residues. The water molecules, oxygen,
nitrogen, and phosphorus atoms are colored pink, red, blue, and
orange, respectively. The hydrogen bonds are indicated by dashed
lines. The main chain nitrogen or carbonyl groups interacting
with the bound NADP+ are labeled by residue numbers. B, a photo
of the ternary complex crystals (0.3 x 0.2 x 0.1 mm). C,
absorption spectrum changes of a ternary complex solution
mixture. A 1:10 dilution of the ternary mixture after NaOH
addition was measured. D, stereo view of the  -chain of bound
15-oxo-PGE[2] in the ternary complex structure. The carbon atoms
of the -chain of 15-oxo-PGE[2]
are colored in cyan, and NADP+ in yellow. The residues from the
same subunit of the bound NADP+ around the -chain hydrophobic pore
are colored in green, and those from the other subunit are in
magenta.|F[o]| -|F[c]| simulated annealing omit electron density
map is contoured at 2.4 (orange) and 3.5 (blue).
The residues Ala-241, Tyr-245, and Met-248 are located on the
loop  E-  F. Tyr-273 was refined
as two conformers. E, a stereo view of the interaction between
the -chain and NADP+. The
hydrogen bonds and the  - orbital interactions
between the nicotine amide ring and the conjugated double bonds
of the -chain are indicated in
dashed lines. The shortest distance of the - orbital interactions is
3.2 Å between the carbonyl oxygen atom of 15-oxo-PGE[2]
and the nitrogen atom of the nicotine amide ring.
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