Aerobic Metabolism Flashcards
Definition
Location
Function of TCA
Oxidation of acetyl CoA => CO2 + H2O
Mitochondrial matrix of all tissues with mitochondria
Energy trapping, biosynthesis of intermediates
TCA in terms of C lost and gained
2C (acetyl CoA) + 4C (oxaloacetate) => 6C (citrate)
6C => 5C + CO2
5C => 4C + CO2
Carbon must be added before decarboxylation
TCA cycle overall
Oxaloacetate + acetyl CoA =citrate synthase=> citrate
Citrate => Isocitrate
Isocitrate => a-ketoglutarate + 2H + CO2
a ketoglutarate => succinylCoA + 2H + CO2
SuccinylCoA => Fumarate + 2H + GTP
Fumarate => Malate
Malate => Oxaloacetate + 2H
Link reaction
Pyruvate + CoA + NAD+ =pyruvate dehydrogenase => Acetyl CoA + CO2 + NADH + H+
Cofactors, thiamine pyrophosphate, lipoid acid, FAD, CoA
Vitamins will affect reaction
Coenzyme A structure
CoA - pantoic acid - B alanine - cysteamine
Condensation reaction
Oxaloacetate =Acetyl CoA, citrate synthase=> citrate
Add more C before decarboxylation
Isomerisation
Citrate <=aconitase=> isocitrate
Make compound more unstable
Aconite needs Fe cofactor
First loss of CO2
Isocitrate =isocitrate dehydrogenase NAD=> a ketoglutarate + CO2 + NADH + H+
Decarboxylation
Oxidation reaction
Second loss of CO2
a ketoglutarate + CoA =ketoglutarate dehydrogenase NAD+=> SuccinylCoA + CO2 + NADH + H+
Make compound more unstable and decarboxylation
Trapping thioester bond energy as GTP
SuccinylCoA =succinate thiokinase GDP + Pi=> Succinate + GTP + CoA
GTP produced for protein synthesis purposes
Conversion of succinate to fumarate
Succinate =succinate dehydrogenase FAD=> Fumarate + FADH2
Oxidation, loss of H
Conversion of fumarate to malate
Fumarate =fumarase + H2O=> malate
Conversion of mlatae to oxaloacetate
Malate =malate dehydrogenase NADH=> Oxaloacetate + NAD+
Oxidation
Role of FAD as H acceptor
FAD + 2H+ + 2e- <=> FADH2
Generation of ATP via oxidative phosphorylation
Reoxidation of NADH => NAD+ occurs by transfer of 2H to cytochrome chain carriers
Pair of H atoms transferred to O2 =>H2O
Results in synthesis of <3ATP from
Describe the ETC
Complex 1 pumps H+ into inter membrane space from NADH=>NAD+
Complex 2 for FADH2 => FAD
Complex 3 and 4 pumps H+ into intramembrane space
Electrons released in C1 passed to C2, 3, 4
Higher conc of H+ on inter membrane space than inner mitochondrial matrix, reenter via ATP synthase pump, synthesis ATP from ADP and Pi
Energy yields of TCA cycle
3 enzyme reaction produce NADH and H+
1 enzyme reaction produces FADH2
1 enzyme reaction produces GTP
3 x 2.5 ATP
1 x 2 ATP
1 GTP
Total, 10 ATP (new total)
Approximation for ATP synthesized with OP
Irreversibility of key stages
Citrate synthetase
Isocitrate dehydrogenase
Ketoglutarate dehydrogenase
All irreversible, highly exergonic
Rate of TCA cycle regulated by feedback inhibition of key enzymes
Isocitrate dehydrogenase
ADP activates
NADH inhibits
Rate of TCA cycle regulated by feedback inhibition of key enzymes
Ketoglutarate dehydrogenase
NADH inhibits
SuccinylCoA inhibits
Rate of TCA cycle regulated by feedback inhibition of key enzymes
Citrate synthetase
NADH inhibits
SuccinylCoA inhibits
Biosynthetic role of TCA cycle
Citrate
Citrate => fatty acids, sterols
Biosynthetic role of TCA cycle
a ketoglutarate
A ketoglutarate <=transamination=> glutamate => other AA, purines
Biosynthetic role of TCA cycle
Malate
Malate <=malic enzyme=> pyruvate
Biosynthetic role of TCA cycle
Oxaloacetate to sugars
Oxaloacetate <=PEP carboxylase=> phosphoenol pyruvate => glucose
Biosynthetic role of TCA cycle
Oxaloacetate to AA
Oxaloacetate <=transamination=> aspartate => other AA, purine, pyramidine
Biosynthetic role of TCA cycle
Pyruvate to oxaloacetate
Pyruvate carboxylase
