Chemistry Reference
In-Depth Information
REACTIVE OXYGEN SPECIES
A number of enzymatic and nonenzymatic processes can produce reactive
oxygen species (ROS) in mammalian cells. ROS include
O
−•
,
1
O
2
, O
3
, and
•
OH,
which are involved in cardiovascular diseases, asthma, diabetes, and asthma
[1-3]. Some of the important inputs of ROS are lipoxygenase, mitochondrial
respiratory chain, xanthine oxidase, nicotinamide adenine dinucleotide phos-
phate (NADPH) oxidases, uncoupled nitric oxide synthase (NOS), and myelo-
peroxidase (MPO) [4]. Impairment of cellular functions, cellular apoptosis, and
killing of pathogens may be associated with high levels of ROS. ROS can
modify proteins by oxidizing amino acid residues, which can lead to fragmenta-
tion of the polypeptide chain, oxidation of amino acid chains, and generation
of protein-protein cross-linking [5-7]. This chapter begins with the discussion
of different approaches to generate ROS in order to study their reactivities
with protein residues, followed by reaction pathways of the mechanisms
involved in the oxidation of proteins by ROS [5, 8-15].
4.1 SUPEROXIDE
4.1.1 Generation
Several techniques have been used to produce superoxide (
O /HO
2
•− •
) to study
its reactions. These techniques include pulse radiolysis, UV photolysis, and
2
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