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
What is the methyl trap?
Without B12, 5 methy FH4 wouldn’t beable to be regenerated to FH4.,
-low B12 could cause a FH4 defficency.
What happens when FH4 and Serine meet?
If B6, pyridoxyal phosphate is around glycine comes out and 5,10 FH4 is created,
What are 5 SAM reaction?
- Nore Epi - EPI
- guanidinoacetate - creatine
- nucleotides - methylated nucleotides
- phosphatydal ethanolamine - phosphatidylcholine
- acetylserotonin - melatonin
what 4 proteins can be degraded to succinyl CoA?
- valine
- isoleucine
- threonine
- methionine
Where do isoleucine, threonine and valine meet?
At propionly CoA
What is required to turn propionly CoA to Methylmalonly CoA?
Biotin - CO2- one carbone donor
What is required to turn Methylmalonly CoA to succinyl CoA
B12 -
An elevation in what would indicate a B12 deficiency?
- homocystine
- methylmalonic acid.
what is the common intermediate in the catabolism of valine, isoleucine, threonine and methanoine?
methylmalonyl CoA
