V. De novo Synthesis of Fatty Acids
Acetyl Groups and Reducing Equivalents
Acetyl groups are produced in the mitochondria by pyruvate
dehydrogenase, and are transported to the cytoplasm.
- Citrate synthase converts acetyl CoA and oxaloacetate
to citrate.
- Citrate exits the mitochondria on the citrate-malate
antiport.
- In the cytoplasm citrate is cleaved by the citrate
cleavage enzyme to regenerate oxaloacetate and
acetyl CoA.
- Oxaloacetate in the cytoplasm is reduced to malate by
NADH from glycolysis; this supplies the malate for the
citrate-malate antiport.
NADPH is produced mostly by the hexose monophosphate
pathway.
The malic enzyme might also contribute to NADPH
production.