Fatty Acid and TAG Synthesis Flashcards
Fatty acyl-CoA desaturase
introduce double bonds in FAs at position 5, 6, or 9
Site of Fatty acid synthesis
Cytosol of Liver and mammery glands
Fatty acid synthase
Main catalytic enzyme for elongation. Active in the dimeric form.
Catalyzes the 7 steps of FA synthesis linking units of Malonyl CoA to ultimately form Palmitoyl CoA.
Requires 2 NADPH & 1 ATP
Unregulated by Insulin
Location of elongation of FAs
Membrane of the ER
Location of desaturation of FAs
ER Matrix
ATP Citrate Lyase
Converts citrate back to OAA and Acetyl CoA in the cytosol of liver cells.
Requires ATP
Fatty Acid Desaturation System
Introduces double bonds to FAs. (5,6,9)
Uses Fatty acyl-CoA desaturase and 2 Cyt B5.
Cyt B5 (Fe++) is replenished by its reductase (FADH2) which in turn is replenished by NADPH
Repetitive Four steps of FA synthesis
Condensation, Reduction, Dehydration, Reduction
Enzymes:
Acetyl Condensing Enzyme, Beta Ketoacyl Reductase, Beta-hydroxyacyl dehydratase, Enol reductase
Reduction steps use NADPH
Acetyl CoA Carboxylase
Converts Acetyl CoA to Malonyl CoA.
Requires Biotin, CO2, and ATP
Rate limiting step of FA synthesis
Activated by Citrate
Inhibited by long Chain FA CoA (Palmitoyl CoA) Glucagon, Epinephrine, Norepinephrine (phosphorylation)
Thioesterase
Releases Palmitate from the Acyl Carrier Protein of FA synthesis
Hormone Sensitive Lipase
Breaks down TAGs to Free FA and Glycerol
Malic Enzyme
Converts Malate to Pyruvate and CO2.
Requires NADP+
Produces NADPH utilized by FA synthesis
Glycerol Phosphate Dehydrogenase
Converts Dihydroxyacetone Phosphate to Glycerol Phosphate in the liver and adipose tissue.
Requires NADH
Glycerol Kinase
Converts glycerol to glycerol phosphate in the liver
Requires ATP
Phosphatidic Acid
Diacylglycerol Phosphate
