Figure 2.
FIGURE 2. Difference omit map for the heme moiety and two
water molecules (blue) within the active site pocket of ChuS
contoured at 2 in the R[3] space
group. Heme and waters were omitted from refinement prior to map
calculations. Residues contributing to heme stabilization
include the non-polar series Leu-90, Leu-92, Phe-102, Val-192,
and Phe-243 and the polar series Arg-100, His-193, Arg-206,
Met-241, Lys-291, Gln-313, Tyr-315, and Arg-318. Heme is
therefore mainly coordinated by the C-terminal half but also by
a distant residue, Arg-100 from the N-terminal half. A network
of hydrogen bonds is formed between Arg-100 and the iron atom of
the heme group via two water molecules (dotted lines). In this
orientation, the propionic side chains of the heme group point
toward the protein interior, exposing the -meso carbon edge
(black arrow). This presentation of the -meso edge may
facilitate electron attack during heme degradation.
The above figure is reprinted
by permission from the ASBMB:
J Biol Chem
(2006,
281,
36776-36782)
copyright 2006.
in the R[3] space
group. Heme and waters were omitted from refinement prior to map
calculations. Residues contributing to heme stabilization
include the non-polar series Leu-90, Leu-92, Phe-102, Val-192,
and Phe-243 and the polar series Arg-100, His-193, Arg-206,
Met-241, Lys-291, Gln-313, Tyr-315, and Arg-318. Heme is
therefore mainly coordinated by the C-terminal half but also by
a distant residue, Arg-100 from the N-terminal half. A network
of hydrogen bonds is formed between Arg-100 and the iron atom of
the heme group via two water molecules (dotted lines). In this
orientation, the propionic side chains of the heme group point
toward the protein interior, exposing the 
-meso carbon edge
(black arrow). This presentation of the