2: Fatty Acid Synthesis Flashcards
What is the major source of carbon for FA synthesis?
Dietary carbs
Organs where FAS occurs
Mostly liver + adipose, brain, kidneys, lactating mammary glands
Two ends of a fatty acid
Carboxyl end, methyl end
Three phases of fatty acid synthesis
- Cytosolic entry of acetyl CoA
- Generation of malonyl coA
- FA chain formation
What enzyme does malonyl coA inhibit?
Carnitine acyltransferase
Enzyme that adds 2C from malonyl coA to a growing fatty acyl chain in seven reactions to make palmitate
Fatty acid synthase (FAS)
Describe the FAS complex
Large, multi-enzyme complex with two identical dimers head-to-tail; with seven different enzymes + acyl carrier protein (ACP)
Four steps in a cycle of FAS
- Condensation
- Reduction
- Dehydration
- Reduction
What induces gene expression of acetyl coA carboxylase and FA Synthase?
Low fat / high carb diet
Citrate lyase: stimulated by what three things? Inhibited by what two things?
Stimulated by: phosphorylation, glucose, insulin
Inhibited by: PUFAs, leptin
Acetyl coA carboxylase: which form is active/inactive?
Polymeric form: active
Monomer/dimer: inactive
Three enzymes regulated in fatty acid synthesis?
- Citrate lyase
- Acetyl coA carboxylase
- FA synthase
Is acetyl CoA active or inactive when phosphorylated?
Dephosphorylated = active
Two things that stimulate acetyl CoA carboxylase
Citrate, insulin
Four things that inactivate acetyl coA carboxylase
LCFAs, epi, glucagon, AMP
