Synthesis and Catabolism of Porphyrins Flashcards
all carbons in the porphyrin ring are derived from
Succinyl-CoA amd glycine
what is the overal rxn of heme synthesis
8 GLY + 8 succinyl CoA = porphyrin, 8 CO2 + 4 NH4
what is the cofactor required for heme synthsis
B6
where does heme synthesis span
mitochondria and cytosol
heme synthesis negatively regulates itself at the _____ _____ step
ALA synthase
heme synthesis requires what three things
glycine, succinyl-CoA, and B6
heme synthesis is inhibited by ______
lead
Can Fe levels play a role in control of translation of ala synthase mRNA
yes
how does heme regulate its own synthesis
- repressing synthesis of ala synthase
- inhibit movement of ala synthase into mitochondria
what kind of porphyria is characterized by episodic acute neruovisceral attacks
acute
what kind of porphyria is characterized by light sensitive lesions
non-acute
what porphyria is associated with a dysfunctional porphobilinnogen deaminase
acute intermittent porphyria
what kind of porphyria is associated with a dysfunctional uroporhyrinogen decarboxylase
porphyria cutanea tarda
what is the treatment for patients with PCT
reduce skin exposure (most common non-acute)
what are the treatments for AIP
hospitalizations, high carb diet, medications that blcok heme synthesis
what is heme broken down into
biliverdin and then bilirubin
bilirubin-albumin is considered
unconjugated; indirect
bilirubin diglucuronide is considered
conjugated; direct
a rare neruological condition that occurs in some newborns with severe jaundice
kernicterus
what is the name of the serum bilirubin test
van den berghs test
how does the liver rid the body of bilirubin
bilirubin is taken up by hepatocytes and secreted into the bile, which is excreted into the intestine
increased Tbill causes
jaundice
causes of jaundice
increased bilirubin production (hemolytic anemias)
problems with liver
obstruction of bile duct
what are possible problems if direct bilirubin is normal
hemolysis, viral hepititis, cirrhosis
