- In the course of the reaction of EC 1.11.1.15, its cysteine residue
is alternately oxidized to the sulfenic acid, S-hydroxycysteine,
and reduced back to cysteine.
- Occasionally the S-hydroxycysteine residue is further oxidized to the
sulfinic acid S-hydroxy-S-oxocysteine, thereby inactivating the
enzyme.
- The reductase provides a mechanism for regenerating the active form
of peroxiredoxin, i.e. the peroxiredoxin-(S-hydroxycysteine) form.
- Apparently the reductase first catalyzes the phosphorylation of the
-S(O)-OH group by ATP to give -S(O)-O-P, which is attached to the
peroxiredoxin by a cysteine residue, forming an -S(O)-S- link between
the two enzymes.
- Attack by a thiol splits this bond, leaving the peroxiredoxin as the
sulfenic acid and the reductase as the thiol.
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