Redox Biology Flashcards
What does Redox stand for?
Reduction and Oxidation
what is OILRIG?
Oxidation Is Loss (Of Electrons) Reduction Is Gain (Of Electrons)
What is a ROS?
Reactive Oxygen Species
What is Superoxide?
Oxygen with an extra electron(O2e-). A free radical
What is another name for ROS?
RONS: Reactive Oxygen Nitrogen Species
What are free radicals?
Any species capable of independent existence that contains 1 or more unpaired electrons.
What is the relationship between ROS and Free Radicals
All Free Radicals are ROS but not all ROS are free radicals
What are some free radicals apart from superoxide?
Hydroxyl radical
Nitric Oxide
What is an example of a ROS that isn’t a free radical?
Hydrogen Peroxide, H2O2
What are the two types of Antioxidants?
Dietary and Enzymatic
Give some examples of dietary antioxidants
Vitamin C and E
What is a key enzymatic antioxidant?
SOD; Superoxide Dismutase
What is a key antioxidant cofactor, and what is it called when reduced or oxidised?
Glutathione (reduced; GSH. oxidised; GSSG)
What is Oxidative Stress?
When the ROS outweigh the antioxidants
What is Redox Balance?
The ratio of ROS to Antioxidants
Is ROS always bad?
No. Low levels of ROS cause adaptation, only when the levels get too high do they cause damage.
What is the relationship beteen exercise intensity/volume and ROS?
Low intensity is associated with low ROS production, and so adaptation. High intensity associated with higher ROS production, and so damage.
What is the relationship between activity level and ROS concentration?
High when sedentary/inactive, decreases until you ebecome active, but starts to increase as you become very active/elite, though not as high as sedentary.
Other than Biomarkers, how do you indirectly measure ROS?
Place a probe into contracting muscle, infuse a liquid into the probe that would be oxidised by ROS. Measure how much of it is oxidised as it comes out of the muscle
How do you use biomarkers to measure ROS?
- Measure the concentration of antioxidants
- Measure biomarkers in plasma, muscle or cells that are linked to changes in protein, lipids or DNA. (e.g. pentane in exhaled air, or MDA due to lipid peroxidation by ROS)
When does peak damage to proteins occur after exercise?
4 hours post
When does Glutathione hit lowest levels after exercise?
2 hours post
How is cortisol affected by exercise?
The greater the intensity of exercise the greater the cortisol secretion
What role does AMP play in redox biology?
It is a byproduct of recycling ATP that needs to be removed, and produces Uric acid as a result
What is the first step of AMP being removed from the cell?
Turned into IMP and NH3 using water, and Adenylate Deaminase.
What is IMP converted into?
Inosine, which, with inorganic phosphate, converts to hypoxanthine
What is hypoxanthine converted to?
Xanthine, then Uric Acid
What is the relevance of Uric Acid in Redox balance?
Uric Acid leads to an antioxidant response
What are the two methods by which AMP is converted to ammonia and uric acid?
Xanthine Dehyrogenase system and Xanthine Oxidase system.
What system of AMP breakdown is primarily used in tissue hyperoxia?
Xanthise dehydrogenase
What system of AMP breakdown is primarily used in tissue hypoxia?
Xanthise oxidase
Explain the Xanthine Dehydrogenase system
Hypoxanthine is converted to Xanthine, then Uric Acid, by oxidising NAD to NADH
Explain the Xanthine Oxidase system
Hypoxanthine is converted to Xanthine then Uric acid, by oxidising oxygen to superoxide.
What is a biomarker of DNA damage?
8-oxoguanine
