Folate Flashcards
The addition of a methyl group to homocysteine to make methionine comes from what cofactor?
Methyl B12
Tetrahydrofolate is synthesized in our bodies by this enzyme
Dihydrofolate reductase
Where does the methyl group on Methyl B12 come from?
MTHF
What nucleic acid synthesis step requires THF?
dUMP -> dTMP
What is leucovorin?
A naturally occurring folate replacement that doesn’t need DHFR
What B12 subtype is given to treat cyanide poisoning and is bound to plasma proteins (longer time in serum)?
Hydroxocobalamin
Where is folate absorbed and where (and how long) is it stored?
Absorbed: Small intestine
Stored: Liver
How long: 4-6 months
The absorption of B12 from the intestine requires ______.
acidity and intrinsic factor
Where and how long is B12 stored?
Where: Liver
How Long: ~5 years
Decreased expression of this protein in cancer cells allows for rescue therapy of normal host cells by leucovorin when given high doses of methotrexate.
Reduced Folate Carrier
Mutations in this enzyme cause for an increased resistance to methotrexate therapy.
Reduced Folate Carrier
This enzyme transports folate»»>methotrexate, and makes certain cancers more susceptible to folate inhibitor therapy.
Folate receptor
What tissues have a higher expression of folate receptor?
Kidney, lungs, choroid plexus, placenta
Folate is better retained in cells and is a better substrate for certain enzymes when ______ is added to it by ______.
polyglutamate
folylpolyglutamate synthase
This medicine is a competitive inhibitor of DHFR.
Methotrexate
