Biochem Pathways Flashcards
(27 cards)
Folate deficiency manifests itself as macrocyclic anemia. What is the biomarker for folate deficiency
Elevated homocysteine
Folate needs for THF synthesis and other synthetic pathways such as methionine synthesis. If no THF, homocysteine accumulates.
How can you tell if macrocytic anemia is caused by folate deficiency vs. B12 (methylcobalamin deficiency)?
Macrocytic anemia caused by lack of B12 will have elevated homocysteine AND elevated methylmalonic acid levels
Macrocytic anemia caused by lack of folate causes only elevated homocysteine. Methylmalonic acid levels are NORMAL
What are the carbon carriers in one carbon metabolism?
SAM & THF
What metabolic pathways involve one carbon metabolism? (5)
DNA methylation Nucleotide synthesis AA synthesis NT synthesis Epinephrine synthesis
That can tetrahydrofolate (THF carry)? (4)
Methylene
Methyl
Formyl
Methenyl
What can S-adenocylmethionine (SAM) carry? (1)
ONLY Methyl groups
What enzyme is used for the following?
Folate —->dihyrdofolate —-> THF
Dihydrofolate reductase
Which nucleosides are purines?
Adenine & Guanine
Which substances are involved in PRPP synthesis?
ATP
Ribose-5-P ——->5-phosphoribosyl-1-pyrophosphate
Enzyme: PRPP synthetase
What is the significance of glutamine hydrolysis in purine formation?
Gln hydrolysis makes ammonia which adds N9 in in de novo purine synthesis
Which 2 components are needed for adenosine monophosphate (AMP) synthesis?
Aspartate (using GTP)
Nucleotide vs nucleoside
NuceloSide = base + sugar NuceloTide = base + sugar + Pi
*remember S comes before T so it has less stuff
Which enzyme catalysis the formation of PRPP? And what else is required?
Ribose 5P ——-> PRPP
Enzyme: PRPP synthetase
ATP is also required
What is sequence of GMP formation?
IMP —> XMP (xanthylate) —> GMP
1st rxn requires: NAD+ —> NADH
2nd rxn requires: ATP —-> ADP & the addition of NH3
What is the sequence of AMP formation?
IMP —> Adenylosuccinate —> AMP
1st rxn needs: GTP—> GDP & Aspartate
Which organ manages ammonia and is key for purine synthesis?
The liver
What is needed to form carbamoyl phosphate?
2 ATP
Bicarbonate (HCO3-)
Ammonia (NH3)
CPS 2 (carbamoyl phosphate synthetase II)
Which nucleic acids are pyrimidines?
Cytosine
Thymine
Uracil
pyrimidines are smaller molecules even tho the name is longer
How is carbamoyl phosphate converted to ororotate?
Carbamoyl phosphate + aspartate - Pi = carbamoyl aspartate
Carbamoyl aspartate cyclizes —> dihydroorotate
Dihydroorotate oxidizes —> orotate
How is OMP converted to UMP?
OMP has to be decarboxylated
Enzyme: orotidylate decarboxylase
4 steps in pyrimidines synthesis
- Carbamoyl phosphate formation
- Carbamoyl phosphate —> orotate
- Orotate + PRPP —> OMP
- Base formation of UMP, TMP, CMP
Ribonucelotide reductase
Catalyze replacement of 2’ OH group with Hydrogen
UMP—>dUMP
Also:
ADP —> dADP, GDP —> dGDP, CDP —>dCDP, UDP—>dUDP
What disease is caused by adenosine deaminase deficiency?
Result?
Tx?
SCID: Severe combined immunodeficiency disorder
Results in: recurrent infections d/t loss of t-cells
Tx: gene therapy
Gout is secondary to which condition?
HypEruricemia
