Antioxidants (Diabetes) - Prof. Coleman Flashcards
What systems have been evolved as protective measures against reactive species produced by cells?
Superoxide dismutase, catalase, and the GSH system.
What is superoxide dismutase?
An enzyme that converts superoxide to oxygen, forming hydrogen peroxide in the process. It is found in all tissues in several variants.
What two variants of superoxide dismutase are there?
A copper/zinc based version (SOD1), and a manganese-based version.
Where is the copper/zinc based version of superoxide dismutase found?
In the cytoplasm.
Where is the manganese-based version of superoxide dismutase found?
In the mitochondria.
Mutations of the copper/zinc based superoxide dismutase enzyme (SOD1) is linked with what disease?
ALS (amyotrophic lateral sclerosis).
What are the consequences of mutant SOD1?
Mutant SOD1 fails to remove superoxide which induces neuronal apoptosis.
What does the catalase enzyme do?
Catalase converts hydrogen peroxide from metabolic processes to oxygen and water. Catalase also attenuates some toxins through peroxidation reactions.
Describe the catalase enzyme.
Catalase is a haemoprotein found in the peroxisome.
How does catalase work?
They are redox enzymes, their haem iron is oxidised by one molecule of hydrogen peroxide; the oxyferryl species is reduced by another hydrogen peroxide forming water and oxygen and regenerating the enzyme.
What substance partially controls SOD and catalase? How does age relate to this?
Melatonin. Melatonin falls with age, leading to an increase in oxidative stress-related disease.
What amino acids is GSH made out of?
Cysteine, glycine, and glutamate.
Describe GSH.
GSH is a thiol. Thiols repair and prevent a change in structure so preserving function. Thiol levels must not fall or oxidative damage outstrips repair.
Cells must maintain what percentage of GSH as thiol?
95%.
How many known cellular functions does GSH have?
30+.
