Structure of
Nitric Oxide Synthase Oxygenase Dimer with Pterin and Substrate.
B.R. Crane, A.S. Arvai, D.K. Ghosh, C. Wu, E.D. Getzoff,
D.J. Stuehr and J.A. Tainer.
Science 279, 2121-2126,
1998. Visit
Science Magazine Online
Pterin interactions in the substrate-binding channel. Electron
density showing well-ordered H4B bridging the dimer
interface.
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Stereoviews of the NOS a-bfold and dimer
assembly.
(A) The symetric iNOSox dimer viewed along the
crystallographic twofold axis.
(B) iNOSox dimer shown rotated 90 degrees about the
horizontal axis from (A).
(C) Solvent-accessible surface of the iNOSox dimer
color-coded by residue conservation.
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Residue function, secondary structure and contributions to the dimer
interface mapped onto the iNOS sequence.
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image (435 KB).
The iNOSox dimer interface.
(LEFT) Ca trace of one iNOSox
subunit dissociated from the dimer and viewed directly into the dimer
interface.
(STEREO-RIGHT) The buried surface of the dimer interface color-coded by
residues
contributed from the regions categorized and colored in LEFT.
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Conformational changes in the iNOSox subunit on
dimerization.
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image (246 KB).
Pterin interactions in the substrate-binding channel. Stereoview
of the hydrogen bond network coupling pterin binding,
dimerization, L-Arg binding and heme activity.
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Ligand binding in the active center.
(A) The H4B-bound iNOSox dimer (yellow
carbons, red oxygens, and blue nitrogens) without substrates or
inhibitors, viewed down the active channel and shown with its sA-weighted
2Fobs-Fcalc electrond densit map
(contours: purple - 1.4s, red - 4.0s, cyan - 10s.
(B) L-Arg in the substrate binding site from a view rotated roughly 180
degrees about the vertical axis compared to (A).
(C) SCit in the substrate binding site viewed as in (B).
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