Week 5 Flashcards
What is oxidative stress
Results form imbalance between the levels of reactive oxygen species and antioxidants
How can oxidative stress occur
If there is an excess level of ROS or a depleteion in AOX
What is an antioxidant
A molecule which protects a biological target against oxidative damage
What are the two groups of antioxidant
Enzymes (proteins) and low molecular weight non-protein organic molecules
What are the antioxidant enzymes
Catalases
Glutathione peroxidases
Peroxidases
Peroxiredoxins
SUperoxide dimutases
Thioredoxin
What are oxidants
Recative molecules that are produced both inside your body and the environment that can react with other cellular molecules such as protiens
What is the most common type of oxidant in the cells
Reactive Oxygen Species (ROS) it include Non-radicals and radicals
What are free radicals
ANy molecules containing one or more unpaired electrons
What are examples of non radicals
Hydrogen peroxide
Hypochlorous acid
Peroxynitrite
Singlet oxygen
ozone
What are some examples of radicals
Hydroxyl
Superoxide
Lipid peroxyl
Nitric oxide
What is oxygen in its ground state
Has two unpaired electrons with parallel spins (biradical)
What does oxygen being bi radical do
Unlikely to particpate in recations with stable organic molecules that are arranged in pairs with antiparallel spins unless oxygen is activated
How can oxygen be activated
If electrons are transferred to O2 one at a time producing mono-radical or non-radical molecules
What are the three types of ROS
Superoxide anion radical
Hydrogen peroxide
Hydroxyl radical
How are oxygen radicals formed
One electron reduction leads to the formation of superoxide anion radical then reductions of superoxide (addition of two electrons) produces hydrogen peroxide if it takes third electron you have hydroxyl radical
What happens once the hydroxyl radical is formed
can be reduced with an electron to from water (4 electron reduction of oxygen)
What are other ROS that can also be converted
Peroxynittrite (reaction of superoxide and nitric oxidie) and hypochlorous acid (hydrogen peroxide and chlorine)
Which radical is produced non-enzymatically
Hydroxyl radicals
How can hydroxyl radicals be produced
Radiation induced homolytic fission or photolytic cleavage
How cna hydroxyl radicals in vivo generate
Through a reacation of metal ions such as iron
How many grams of iron are in the body
4
What si the recation called that hydroxyl radicals are produced
Fenton reacation which is oxidation of a ferrous iron with hydrogen peroxide
What is ferric trivalent ions and ferrous ions
Ferrous iron is iron two and ferric iron is iron 3
What happens with the ferric trivalent ions formed in the fenton reacation
Need to be re-generated back to ferrous ions whihc happens in a recation with superoxide anion radical