Fatty Acid Synthesis Flashcards
Where does FA anabolism take place?
in the cytoplasm (whereas FA oxidation/catabolism occurs in the mitochondrial matrix)
what is considered to be the “committed step” in FA synthesis?
the activation of acetyl-CoA (2 C molecule) in a carboxylation reaction by acetyl-CoA carboxylase to become malonyl-CoA (a 3 carbon molecule)
This step requires ATP
what enzyme activates an acetyl-CoA into a malonyl-CoA?
acetyl-CoA carboxylase
After acetyl-CoA is activated into malonyl-CoA, which enzyme is responsible for linking these units together with its 2 domains of acyl carrier protein and cysteine residue?
fatty acid synthase
Steps taken by fatty acid synthase for FA synthesis:
1) acetyl CoA binds to the ____ domain
2) acetyl CoA is then shifted to another domain on the enzyme with a ______
3) a malonyl-CoA binds to _____
4) the acetyl group condenses with the malonyl group, as the malonyl group is ____, causing removal of ____
5) the ____ domain now holds a 4 carbon unit, which undergoes 2 reductions by _____
6) The saturated 4 carbon unit is shifted to the domain with the _____, while another malonyl CoA binds to the ____ domain.
7) The process then repeats until a ___ carbon FA is generated
- ACP
- cysteine residue
- ACP domain
- decarboxylated, removal of CO2
- ACP, 2 reductions by NADPH (1 NADPH is used for each reduction, ultimately causing the removal of 1 carbonyl O, leaving the other carbonyl unaffected)
- cysteine residue, malonyl-CoA binds to the ACP domain
- 16
Once a 16 carbon FA is generated, additional ____ aid in further modification of the FA
enzymes
What is the reducing agent for FA synthesis?
NADPH
After the acyl unit is shifted from the cysteine residue onto the malonyl-CoA (on the ACP domain), how many NADPH are required to for reduction before the new acyl unit is moved to the cysteine residue?
2
How many ATP are required to activate the acetyl-CoA into a malonyl-CoA
1 ATP
How many carbons does malonyl-CoA have?
3
when is CO2 utilized as a reagent in fatty acid synthesis and when is CO2 released as a product in fatty acid synthesis?
CO2 is utilized as a reagent when activating acetyl-CoA into malonyl-CoA via carboxylation
CO2 is given off as a product during the joining of the acetyl-CoA or acyl unit on the cysteine domain to the malonyl-CoA unit on the ACP domain (the carboxylate anion portion of the malonyl-CoA leaves as CO2)
During FA synthesis, fatty acid synthase requires ____ NADPH to convert a 6 C acyl group into a 10 C acyl group.
4 NADPH; 1 round of reduction (which requires 2 NADPH molecules) is required per 2 C addition. Therefore, 2 rounds of reduction x 2 NADPH molecules per reduction = 4 NADPH molecules.
