Figure 5.
Figure 5. Reaction mechanism of the R733 ArsC arsenate
reductase. The mechanism is consistent with the crystal
structures described in Table 1 Go-. In step
1, the free enzyme (structure I) forms the observed covalent
intermediate with arsenate (Martin et al. 2001). In step 2, this
intermediate is glutathionylated, a structure that has not yet
been obtained. In step 3, As(V) is reduced to As(III), producing
a dihydroxy arsenite intermediate (structures VI, IX). In step
4, the novel monohydroxy intermediate with a positively charged
arsenic is formed (Martin et al. 2001). Finally, in step 5, the
free enzyme is regenerated (structure I).
The above figure is reprinted
by permission from the Protein Society:
Protein Sci
(2004,
13,
2330-2340)
copyright 2004.
. In step
1, the free enzyme (structure I) forms the observed covalent
intermediate with arsenate (Martin et al. 2001). In step 2, this
intermediate is glutathionylated, a structure that has not yet
been obtained. In step 3, As(V) is reduced to As(III), producing
a dihydroxy arsenite intermediate (structures VI, IX). In step
4, the novel monohydroxy intermediate with a positively charged
arsenic is formed (Martin et al. 2001). Finally, in step 5, the
free enzyme is regenerated (structure I).