Figure 1.
Figure 1. Crystal structures of the six nitrite-soaked I257
variants in the upper six panels. Hydrogen bonds are shown as
dashed gray lines with ligand bonds drawn in solid, dark gray
lines. Water molecules are drawn as aquamarine spheres. Copper
atoms are gray; nitrogen atoms are dark blue, oxygen atoms are
red, and sulfur atoms are yellow. The backbone of monomers B and
C are shown in burgundy and in teal, respectively. Bonds of the
nitrite molecule bound in the active site are white. Omit Fo-Fc
electron density maps are contoured at 4 and drawn as
a green wire mesh. Panels A and B depict the multiple
conformations of the nitrite bound in the active site of the
Ile257 variants and including nitrite bound to the oxidized D98N
(black atoms) and H255N (gray atoms) crystal structures
(Boulanger and Murphy 2001). With the exception of the purple
nitrite molecules in panel B, nitrite molecules are blue to red
with increasing specific activity: Red, I257V[NO[2]^-]; orange,
native NiR from Alcaligenes faecalis S-6; light orange,
I257L[NO[2]^-]; yellow, I257M[NO[2]^-]; green, I257A[NO[2]^-];
cyan, I257G[NO[2]^-]; blue, I257T[NO[2]^-].
and drawn as
a green wire mesh. Panels A and B depict the multiple
conformations of the nitrite bound in the active site of the
Ile257 variants and including nitrite bound to the oxidized D98N
(black atoms) and H255N (gray atoms) crystal structures
(Boulanger and Murphy 2001). With the exception of the purple
nitrite molecules in panel B, nitrite molecules are blue to red
with increasing specific activity: Red, I257V[NO[2]^-]; orange,
native NiR from Alcaligenes faecalis S-6; light orange,
I257L[NO[2]^-]; yellow, I257M[NO[2]^-]; green, I257A[NO[2]^-];
cyan, I257G[NO[2]^-]; blue, I257T[NO[2]^-].