27 Reactive Oxygen Species Flashcards
what’s a ROS
oxygen containing compounds that are highly reactive free radicals or can easily convert to highly reactive free radicals
what’s a RNOS
oxygen and nitrogen containing compounds that are highly reactive free radicals
of the 5 most common reactive oxygen species, which ones are free radicals
superoxide and hydroxyl radical
the most potent and dangerous free radical and what makes it so potent
the hyroxyl radical is the most potent free radical, and it initiates lipid per oxidation, a chain reaction in cellular, nuclear, ER and mitochondrial membranes.
2 non-enzymatic reactions which from the Hydroxyl radical
the Fenton reaction and the Haber-Weiss reaction are the two ways Hydroxyl radical are formed
how do free radicals cause oxidative damage
to Lipids
the hydroxyl radical extracts an electron from a polyunsaturated FAs, forming lipid free radicals and peroxides in the membrane, resulting in lipid degradation
how do free radicals cause oxidative damage to DNA
the hydroxyl radical can cause DNA base modifications, strand breaks and attack on the backbone.
how do free radicals cause oxidative damage to Proteins
proteins can fragment, amino acid residues can cross link (aggregate, becoming dysfunctional) with other residues, leading to proteolytic degradation
nitric oxide as a free radical
nitric oxide is an oxygen containing free radical that is both essential to life and toxic, high mobility due to its ability to diffuse
how nitrogen oxide is made
formed in the conversion of Arginine to Citrulline, catalyzed by NO synthase, requires Fe-heme, FAD, FMN and BH4, addition of O2 and NADPH
the three antioxidant defense enzymes
are superoxide dismutase, catalase and glutathione peroxidase
superoxide dismutase and how does it work
superoxide dismutase converts superoxide anion to H202, hydrogen peroxide, a strong initiator of chain rxns
catalase and how does it work
catalase will (1) reduce H202, hydrogen peroxide, immediately to h2O to prevent formation of hydroxyl radials and (2) will also reduce lipid peroxides to a non-toxic alcohol.
glutathione peroxidase and how does it work
glutathione peroxidase will (1) reduce h202, hydrogen peroxide to h2O and (2) also reduce lipid peroxides to non toxic alcohols.. Oxidation of sulfhydryl groups on 2GSH, glutathione to glutathione disulfide, GSSG?
our dietary antioxidants and free radical scavengers are
vitamin E, vitamin C, carotenoids and flavenoids
