Redox reactions Flashcards
Free radicals are..?
Small, diffusible, very reactive, short lives, unstable
What is the order of ROS?
hydrogen peroxide, superoxide anion and then hydroxyl radical (least to most)
How are ROS generated in mitochondria?
Mitochondria (e- transport chain - complex I and III) - autooxidation of ubisemiquinone (this is a free radical) which releases superoxide into matrix and intermembrane space. Can etner the cytoplasm through VDAC
How are ROS generated in cytoplasm?
Xanthine dehydrogenas (XDH) generates hydrogen peroxide whilst creating uric acid and xanthine
How are ROS generated in plasma membrane?
NADPH oxidase
What are positive effects of free radicals?
signal energy overload and decrease energy uptake
oxidize iodide to iodine
Kill pathogens, clean up cells and debris
How does detoxification of superoxide anion radical occur?
By SOD changing it to hydrogen peroxide and then GPO and CAT converting it too water
what do antioxidants do?
Prevent e- transfer from o2 to organic molecules
stabilize free radicals and terminate free radical reactions
What is SOD
superoxide dismutase
produces hydrogen peroxide from superoxide anion
MnSOD (mito) and CuZn SOD (cyto and mito)
What is GSH-PX?
Glutathione peroxidase
converts hydrogen peroxide to water
requires GSH
What is GSH?
non-protein thiol
has roles in immune, proliferation, redox balance and prostaglandin metabolism
what is catalase
heme-containing enzyme making H2O2 to H2O
requires NADPH
WHat are negative ROS effects?
DNA damage, Lipid damage and protein damage
How can you detect superoxide?
MitoSOX red dye
What is electorn spin resonance?
Detects microwave energy absorption and can change with free radicals. Uses EMPO ato make them more stable for measurement
