One Carbon pool Flashcards
What are the 3 one carbon carriers?
- biotin - CO2
- tetrahydrofolate - all states but CO2
- s adenosylmethinine - active methyl
What vitamin is found often in amino acid biosynth reactions?
biotin - is a one carbon carrier
Where is biotin used, 3.
- pyruvate carboxylation
- odd chain fatty acid
- produce malonly coA
what is the principal donor of active methyl groups?
SAM, s adenyl methionine
what is the one carbon that does everything but CO2?
THF - tetrahydrofolate
What must be done to dietary folate for absorbtion?
It must be deconjugated from all but one of its glutimates,
absorbed in monoglutamate form
Where is folate deconjugated, with what?
Brush border of intestinal epithelium
uses a:
-conjugase
-reductase
what must be done to folate once its absorbed?
it must be reconjugated using a cellular conjugase.
What form of folate can not be oxidized?
5-methyltetrahydrofolate - it needs B12
What cycle is used to regenerate SAM?
the methyl cycle - folate
what aa is the immediate precursor of SAM?
Methionine
What happens to SAM when it is hydrolysed?
produces homocystine, t
What enzyme is used to regenerate SAM from homocysteine?
homocysteine methyltransferase
what are the cofactors for homocystein methyltransferase?
- activated methyl from 5-methyl tetrahydrofolate
- B12 - one carbon donor via CO2
How can homocysteine be converted to cysteine?
two steps: Both requiring pyroxidal phosphate B6 cofactor.
- cystathionine synthase
- cysthalionase
