W3-1: Folate/B12 Flashcards Preview

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Flashcards in W3-1: Folate/B12 Deck (15):
1

THF vitamin precursor

Folate (B9)

2

Functional and storage forms of THF

Functional: monoglutamate

3

Congenital defect caused by failure of the neural tube to close prenatally

Spina bifida

4

Hereditary folate malabsorption

Defective intestinal (absorption) and liver (storage) proton-coupled folate transporters

 

-->megaloblastic anemia-dTMP cannot be synthsized from dUMP, RBCs grow but do not divide, WBCs also affected

5

Reduction state-changing folate rxns

Image Preview

6

DHF reductase inhibitors

methotrexate- cancer or RA

trimethoprim-antibacterial

pyrimethamine-antimalarial

7

Action of 5-fluorouracil

inhibit thimidylate synthase

8

THF-methyl group combinations

9

dTMP synthesis

10

Fate of 5-methyl THF

donates methyl to cobalamin

11

2 amino acids that add methyls to THF

  • Tryptophan (fumate)
  • Serine (for methylene)

12

2 useful forms of cobalamin

  • methyl cobalamin
  • adenosyl cobalamin

13

methyl cobalamin rxn

homocysteine-->methionine

(to make cysteine)

14

adenosyl cobalamin rxn

methylmalonyl-CoA ---> succinyl-CoA (to TCA)

**from branched and odd chain fatty and amino acids

15

What is the methyl trap?

when a lack of cobalamin traps all the THF as methyl-THF, unable to particiapte in other one-carbon transfers

(methylene form used to make thiamine)