Selenium & Cr Flashcards
Biological functions of Selenium
Antioxidant
Glutathione Peroxidase reaction (GPX)
Co-dependent on Vit E
Enzymatic conversion T4 to T3
GTX-1
Specific for glutathione (GSH) in most cells and plasma. not reactive for lipid or sterols
Cataylses:
2 x glutathione + ROOH = Glutathione disulphated + ROH + H2o
GTX-GI (2)
Similar function to that but GTX-1 but primarily in intestine
GTX-3
found in the kidneys and secreted into the plasma
basis unclear
GTX-4
Phospholipid hydroperoxide Glutathione peroxidase
- will reduce phospholipids and cholesterol hydroperoxides that are not reduced by GPX-1
- has a boarder detoxifying capacity than GPX-1
DI-I
Iodothyronine 5’-Deiodinase
Major enzyme (90%) converts T4 to T3
Found in ER of liver and kidney cells
DI-2 and DI-3
similar functions
2: brain, skin, adipose
3: fetal liver, CNS, muscle
Where in the environment is selenium
Enriched in soil
From volcanic reactions
describe selenium’s absorption?
hydrophilic and highly absorbed (80-90%)
How is selenium collected from animal products
as selenocysteine and Se-proteins
Can Selenium be toxic?
Yes, TUL: 400-1000 ug/day
can be found in toxic levels in plants
symptoms: brittle nails and hair, garlic breath
>2000ug/day = vomiting, diarrhea, fatigue
>grams/day (heart attach, kidney failure, death)
Chromium oxidation states include
Cr3+ - required for carb and lipid metabolism, essential,
Cr6+ - by-product of manufacturing processes
Upon absorption cr3 is concentrated into 3 primary sites
kidney
muscle
liver
What is the primary carrier for Chromium
Transferrin - from blood to body cells
- from dietary chromium to cellular chromodulin
binding capacities differ for transferrign vs chromodulin
Tf: binds 2 Cr3+
Chromodulin: 4 Cr3+
