Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
11 Cards in this Set
- Front
- Back
|
How is Se homeo maintained?
|
Via urinary excretion as trimethyl Se
|
|
|
Name some Se-dependent enzymes
|
Glutathione Peroxidases (3)
Iodothyronine deiodinase Thioredoxin reductase |
|
|
What are the Gluthathione peroxidases?
What role does Se play? |
cGSH-Px - cellular (widespread)
eGSH-Px - extracellular (plasma & milk) phGSH-Px - phospholipid hydroperoxide **Se is at active site |
|
|
What is their role?
|
ROOH + 2GSH --> GSSG + ROH + H20
Catalyzes hydroperoxide reaction. |
|
|
What is special about ph-GSH-Px?
|
It can react w/FA hydroperoxides esterified onto phospholipids.
|
|
|
What is the role of Iodothyronine deiodinase?
|
Deiodinized T4-->T3
Circulating to active form. |
|
|
What is the role of Thioredoxin reductace?
|
Catalyzes recution ofThioredoxin (NADH dependent)
|
|
|
Describe the synthesis of selenocysteine?
|
Selenocysteine the Se-containing AA in aminals.
tRNA is first charged with serine.: ser + tRNA --> ser-tRNA Then, it reacts with Se (Selenophosphate actually) --> Sec-tRNA Sec is encorporated into protens during translation. Sec is |
|
|
How is selenophosphate created?
What is the enzyme? |
Selenine (O=Se-(OH)2) --> O=Se-OH-OPO3 via selenophosphate synthetase ( a Se containing protein!)
|
|
|
Descibe how sec gets incorporated.
|
mRNA codes for sec using stop codon "UGA". However, unique stem-loop struction on the mRNA causes UGA to be read as "include sec" and not "stop"
|
|
|
What is the deficiency of Se called?
What are the symptoms? |
Keshan's disease
Coughing, difficulty breathing, vomiting. Swollen body, enlarged liver, lungs. Also: cardiomyopathy -very serious and often fatal. |
