(5) Copper is toxic in its unbound form, causes redox imbalance due to its highly redox active nature, which leads to activation of stress sensitive intracellular signaling pathways through Haber-Weiss reaction
(6,7) The present study was undertaken to study the relationship between fasting plasma glucose (FPG) and copper with ceruloplasmin in type 2 DM patients
Hydroxyl radical is also formed in the Haber-Weiss reaction with the participation of hydrogen peroxide, superoxide anion and ferrous cation :
The Haber-Weiss reaction and mechanisms of toxicity.
The sum of reactions 1 and 2 is the Haber-weiss reaction; Transition metals thus play an important role in the formation of hydroxyl radicals.
Destruction of cells also leads to liberation of metal ions which in turn catalyses the formation of ROS through Fenton reaction and Haber-weiss reactions. 
The total reaction is described as Haber-Weiss reaction
(Figure 1), and the net reaction shows that superoxide anion and [H.sub.2][O.sub.2] are converted to oxygen, hydroxide ion, and hydroxyl radical.
Reaction 7 is the Haber-Weiss reaction
, which supports the notion that transition metals play an important role in the formation of hydroxyl radicals.
Although [H.sub.2][O.sub.2] may not cause DNA damage under physiologic conditions, it participates in the metal ion-catalyzed Haber-Weiss reaction
and generates the highly reactive *OH, which can target DNA, resulting in oxidative DNA damage (42).
Fenton reaction (Haber-Weiss reaction
) and myeloperoxidase production of hypochlorite are other in vitro-used systems that mimic oxidative stress.
radical (Haber-Weiss reaction
) or in the presence of [Fe.sup.+2] (Fenton reaction), it causes the hydroxyl radical to form much more rapidly .
([6,7]) However, the ability of iron to cycle between its two stable oxidation states is also potentially to generate reactive oxygen or nitrogen species (ROSs or RNSs) such as hydroxyl radical via Fenton's and Haber-Weiss reactions
However, it can be reduced to the active Fe2+, depending on condition, particularly pH  and oxidized back through Fenton type reactions with the production of hydroxyl radical or Haber-Weiss reactions
with superoxide anions.