Figure 3.
Fig. 3. (A) Scheme of the reaction mechanism of pI258
ArsC. (1) The nucleophilic attack of the thiol of Cys-10; (2)
the formation of a covalent Cys-10-HAsO[ -
]intermediate; (3) the nucleophilic attack of the thiol of
Cys-82 with arsenite release; (4) the formation of a
Cys-10-Cys-82 intermediate and the nucleophilic attack of the
thiol of Cys-89; (5) the formation of a Cys-82-Cys-89 disulfide.
(B-F) A stereo view of the 2F[o] F[c]
electron density maps contoured at 1.0 placed
next to its corresponding reaction step in A. (B) The P-loop
(residues 10-17) in the structure of reduced wild-type ArsC with
Cys-10 in the center of the image. The P-loop is fully
structured, despite the absence of bound oxyanion (2.0 Å).
(C) In the structure of C15A ArsC-HAsO[ -
], an arsenic is covalently bound on Cys-10, surrounded by three
oxygens in a plane and a water molecule opposite the sulfur of
Cys-10 (1.4 Å). (D) Oxidized ArsC C89L with the
intermediate Cys-10-Cys-82 disulfide bond (1.6 Å). (E) A
view on the flexible looped-out region of oxidized ArsC C89L,
where Cys-89 has left the hydrophobic core and is replaced by
Leu-92 upon Cys-10-Cys-82 formation. The electron density in
this highly flexible region is not so well defined. (F) A view
on the surface of oxidized ArsC C10SC15A (6) with the
Cys-82-Cys-89 disulfide bond.
-
]intermediate; (3) the nucleophilic attack of the thiol of
Cys-82 with arsenite release; (4) the formation of a
Cys-10-Cys-82 intermediate and the nucleophilic attack of the
thiol of Cys-89; (5) the formation of a Cys-82-Cys-89 disulfide.
(B-F) A stereo view of the 2F[o] 
F[c]
electron density maps contoured at 1.0 
placed
next to its corresponding reaction step in A. (B) The P-loop
(residues 10-17) in the structure of reduced wild-type ArsC with
Cys-10 in the center of the image. The P-loop is fully
structured, despite the absence of bound oxyanion (2.0 Å).
(C) In the structure of C15A ArsC-HAsO[