Synthesis of FAs and TAGs Flashcards
What can acetyl CoA be produced from?
Pyruvate
Ketogenic AAs
FA oxidation
Alcohol metabolism
How is acetyl CoA moved out of the mitochondria?
OAA is added to form citrate by citrate synthase
Citrate transporter out of mitochondria
OAA removed in cytosol by citrate lyase using ATP
What can occur using the free OAA in the cytosol?
Glucose production - converted to malate - malate converted to pyruvate producing NADPH
What are the two main enzymes of FA synthesis?
Acetyl CoA carboxylase
Fatty acid synthase complex
What are the coenzymes required for FA synthesis?
Biotin
NADPH
Mn
Mg
What is the reaction catalyzed by acetyl CoA carboxylase?
Acetyl CoA to Malonyl CoA using ATP and CO2. Biotin as a coenzyme
Irreversible
How is Malonyl CoA used in FA synthesis?
It enters FA synthase complex where additional malonyl groups are added in 7 cycles until the chain is 16 C long
How does citrate regulate acetyl CoA carboxylase?
Activator
What are inhibitors of acetyl CoA carboxylase?
Malonyl CoA
Palmitoyl CoA
What inhibits the transition between inactive and active forms of Acetyl CoA carboxylase?
LCFA CoA
How will phosphorylation affect acetyl CoA carboxylase?
It deactivates it
How will glucagon and epinephrine regulate acetyl CoA?
phosphorylation
How will insulin regulate acetyl CoA?
Dephosphorylation
How is palmitate elongated?
Activated to palmitoyl CoA
Lengthened by 2 C units using Malonyl CoA
Where does desaturation of FAs occur?
sER
What is required for desaturation of FAs?
Fatty acyl-CoA
Desaturases
Cytochrome b5
NADH
O2
What are the major organs of TAG synthesis?
Liver
Adipose tissues
Lactating mammary glands
What are the components required for TAG synthesis?
Acyl CoA
Glycerol-3P
What is the first step of TAG synthesis?
Activation of FAs to Acyl-CoA by Acyl-CoA synthetase using ATP and Mg
What is the second step of TAG synthesis?
Activation of glycerol to alpha-glycero-P ysing glycerokinase and ATP
Or synthesis of alpha-glycero-P from DHAP by glycerol-3P DH using NADH in adipose
What is the third step of TAG synthesis?
Esterification
Alpha-glycero-P + 3 acyl CoA in multiple steps
What enzymes are involved in the third step of TAG synthesis?
Glycerol-3P-acyl transferase
1-acylglycerol-3P-acyl transferase
Phosphotidate phosphohydrolase
Diacylglycerol acyl transferase
