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Figure 2.
FIG. 2. A, comparison of the structures of the iNOSoxy
(green) and nNOSoxy (gray) NPA complexes. There is one
qualitatively different interaction in the nNOSoxy complex that
originates ultimately from Asn-498 located in the substrate
access channel. iNOSoxy has a threonine (T277) at this position.
B, the view onto the heme plane shows the difference in the
positioning of  -strand S15 (F363 to
W366, iNOS numbering) that makes up the back wall of the heme
cavity. Asn-364 limits the space available for the propyl chain
of NPA in iNOSoxy. C-E, for illustration, the cavity between the
backwall and N  of the bound L-Arg is
shown (green mesh) and the NPA coordinates are superimposed on
the corresponding L-Arg complexes. For eNOSoxy (Protein Data
Bank code 4NSE [PDB]
), the coordinates of NPA of the nNOSoxy-NPA complex were used.
In contrast to iNOSoxy (E), the cavity is rather large in
nNOSoxy (C) and eNOSoxy (D), explaining the latter's good
acceptance of inhibitors with bulky groups at the N position. F, -strand
S15 in murine iNOSoxy (green), human iNOSoxy (gray), bovine
eNOSoxy (violet), and human eNOSoxy (red) structures.
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