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Figure 1.
Fig. 1. NOS[ox]  -  fold, dimer
assembly, and likely interaction surface for NOS[red] and
caveolin. (A) The symmetric iNOS[ox] dimer viewed along the
crystallographic twofold axis, showing left (and^ right)
subunits with orange (yellow) winged sheets and
flanking blue (cyan) helices. Ball-and-stick models (white bonds
with red^ oxygen, blue nitrogen, yellow sulfur, and purple iron
atoms) highlight active-center hemes (left-most and right-most),
interchain disulfide^ bonds (center, foreground), pterin
cofactors (white, left-center and right-center), and substrate
L-Arg (green left and magenta^ right). The NH[2]-terminal ends
contribute hairpins
(center top and bottom) to the dimer interface, and the
COOH-termini (lower left and upper right) lie 85 Å apart.
Gray loops (residues 101^ to 107) are disordered. (B) iNOS[ox]
dimer shown rotated^ 90° about a horizontal axis from (A).
Each heme is cupped between the inward-facing palm (webbed sheet) and
thumb (magenta loop in front of left heme and green loop behind
right heme) of the^ "catcher's mitt" subunit fold. (C)
Solvent-accessible surface^ (29) of the iNOS[ox] dimer (one
subunit red, one subunit blue) oriented as in (B) and
color-coded by residue conservation (paler to more saturated
represents less conserved to more conserved) in NOS[ox]
sequences of known species and isozymes. The heme (white^ tubes)
is also solvent-exposed on the side (left subunit) opposite^ the
active-center channel (right subunit) and surrounded by a^
highly conserved hydrophobic surface for NOS[red] and caveolin
binding. (Stereo variations of Figs.
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