One Carbon Metabolism

Question 1

Folate Conjugase

what it does

where is it

inhibited/compromised by?

Answer 1

Polygluts to monoglutamate (folate)

@ jejunum

Inhibited by phenytoin

Compromised by tropical/celiac sprue

Question 2

Leucovorin

Answer 2

Folinic acid (activated folate)-gets converted to THF

bypass metabolic block of methotrexate

no neurotox, no GI tox, no myelosupression

Question 3

PABA

Answer 3

Becomes folic acid in bacteria when use DHPS enzyme

Question 4

SAM

Answer 4

used in DNA methylation and Epi synthesis

after donating methylgroup becomes homocysteiene

Question 5

Homocysteine accumulation

• sx
• related to?

Answer 5

Oxidative damage, inflammation, and vascular disease (cause or marker)

Inversely related to Folate, B12, and B6 plasma levels

Question 6

Folate Trap etiology

Answer 6

B12 slows homocystene and N5 methyl THF to methionine and THF
-folate of cell gets trapped as N5 methyl THF

Without THF avaible tomake other folate types-cell nucleotide supplies are depleted

Question 7

b12 def biomarkers

Answer 7

elevated homocysteine and methylmalonic acid

Question 8

Methylmalonic acid

upstream and downstream

Answer 8

In V and isoleucine degredation and Odd Chain FA degredation

with B12 becomes succinyl coa (for TCA)

Question 9

3 things that make microcytic anemia

Answer 9

def in iron, pyridoxine, ascorbate

Question 10

2 things that make macrocytic anemia and pathway

Answer 10

B12/Folate def

-cells get bigger to divide-but cant syntehsize new DNA (nucear mutration impaired but cyto maturation unimpeded)