Chemistry Reference
In-Depth Information
REACTIVE SPECIES
Reactive intermediates and oxidative damage of proteins are important in
biomedical research due to their roles in pathologies and aging [1-5]. Reactive
species are also associated with important mediators in a wide range of bio-
logical processes such as signaling, for proper synaptic plasticity, and normal
memory [3, 6-9]. Additionally, nitroxidative species contribute to pain and
central sensitization [10, 11]. The amounts of reactive species during neurode-
generative diseases and aging increase to higher levels than the antioxidants
present in a cell can handle. The reactive species that participate in a large
number of reactions in diseases [4, 12-17] include both free radicals and non-
radical species (Table 1.1) [18-20]. Reactive oxygen species (ROS) include
superoxide anion (
O
−•
), hydroperoxyl (
HO
•
), alkoxyl (RO
•
), peroxyl (ROO
•
),
hydroxyl radical (
•
OH), hydrogen peroxide (H
2
O
2
), ozone (O
3
), singlet oxygen
(
1
O
2
), and hypochlorous acid (HOCl). The ROS initiate many reactions, for
example, the primary mitochondrial ROS,
O
−•
, reacts with superoxide dis-
mutase (SOD) to form H
2
O
2
, which then reacts further with metal ions or
their complexes (Fenton and Fenton-like reactions) to produce
•
OH. Other
intermediates are reactive nitrogen species (RNS), which include nitric oxide
(NO
•
), nitrogen dioxide radical (
NO
•
), peroxynitrite (OONO
−
), peroxynitrous
acid (OONOH), alkylperoxynitrite (ROONO), and nitrosyl (NO
+
).
ROS and RNS are interconnected and cause protein damage in biological
processes.
O
−•
, NO
•
, and ONOO
−
are associated with neuroimmune activation,
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