TCA cycle Flashcards
Vitamin precursor of CoA
Pantothenate
Niacin is for NAD
riboflavin is for FAD and FMN
what can generate Acetyl CoA?
pyruvate acetate ketone bodies fatty acids amino acids
Lack of NADH activates flux through which enzymes?
Isocitrate dehydrogenase
a-ketoglutarate dehydrogenase
malate dehydrogenase
which enzymes in TCA have Fe-S centers?
Succinate dehydrogenase
aconitase
What enzymes in TCA contain bound FAD
succinate dehydrogenase
a-ketoglutarate dehydrogenase
water soluble protein found in intermembrane space
cytochrome c
what generates the proton motive force?
there is an electrical component and an pH driven component
Acetyl CoA and OAA and water =
citrate
via citrate synthase
citrate =
isocitrate via Aconitase
reversible
isocitrate + NAD+ =
a-ketoglutarate + NADH + H+ + CO2
via isocitrate dehydrogenase
a-ketoglutarate + CoASH +NAD+ =
Succinyl CoA + NADH + H+ CO2
via a-ketoglutarate dehydrogenase complex
Succinyl CoA + GDP + Pi =
Succinate + GTP + CoASH
via succinyl CoA synthetase
Succinate + [FAD] =
fumarate + [FADH2]
via succinate dehydrogenase
Fumarate + h2O =
L-malate
via fumarase
L-malate + NAD+ =
OAA + NADH + H+
via malate dehydrogenase
net reaction for TCA
Acetyl CoA + 3 NAD+ + [FAD] + GDP + Pi + H2O =
CoASH + 3 NADH + [FADH2] + GTP + 2 CO2 + 3 H+
Simple combustion of acetate
acetate + 2 O2 + H+ = 2 CO2 + 2 H2o
Anapleurotic reaction of Acetyl CoA
fatty acids
Anapleurotic rxn of a-ketoglutarate
Glutamate which could be used to make purines
anapleurotic rxn of Succinyl CoA
can be used to make d-aminolevulinate which can be used to porphyrins
Fumarate and OAA in an anapleurotic rxn can produce
aspartate which can be used to make pyrimidines
Arsenic poisoning
inhibits dehydrogenases (pyruvate DH and succinate DH) and Complex IV
affects DH in glycolysis and gluconeogenic pathways
so inhibits both aerobic and anaerobic pathways
how is a-ketoglutarate dehydrogenase complex regulated?
AMP activates
NADH inhibits
Succinyl CoA inhibits
How is isocitrate dehydrogenase regulated?
Inhibited by ATP and NADH
upregulated by ADP
how is citrate synthase regulated?
Inhibited by ATP, NADH and Succinyl CoA
how is pyruvate dehydrogenase regulated?
Inhibited by ATP, Acetyl CoA, NADH
upregulated by NAD+ and CoA
how is pyruvate carboxylase regulated?
upregulated by Acetyl CoA
