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).
. 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).