|
Figure 5.
Fig. 5. Comparison of the proximal heme-binding regions of
iNOS[ox] and cytochrome P450s. Structural elements contributing
to the proximal heme-binding regions of iNOS[ox]  114 and
P450[cam] (cyan C  traces)
are substantially different. Only the proximal Cys ligands
(magenta bonds with yellow sulfur atoms, bound to gold^ hemes)
and immediately COOH-terminal three residues (magenta C traces)
have similar conformations. In iNOS[ox], Cys194 lies at the
COOH-terminal end of a helix and precedes an extended^ strand,
whereas in P450[cam], Cys357 lies at the NH[2]-terminal end of a
helix and follows an extended^ strand. Also, these two cysteine
thiolates bind opposite faces of iron protoporphyrin IX. C positions
for iNOS[ox] 114
residues 194 to 197 were superimposed with P450[cam] residues
357^ to 360 and then separated for clarity.
|
