Flashcards in Lipid Metabolism Deck (35):
3 steps of fatty acid synth
1. cytosolic entry of acetyl CoA from mitochondrial matix's TCA
2. Generation of Malonyl CoA
Most impor substrate, rate limiting step
3. FA Chain formation
function of citrate shuttle
1. move acetyl CoA out of mitocondrial matrix to cytosol
does through combining Oxyloacetate and acetyl CoA to make Citrate. ATP Citrate Lyase splits them up again
2. Move and regenerate oxyloacatate back to mitoch. matrix for TCA
What are some inhibitors, promotors of ATP Citrate Lyase?
Inhb. = PUFA, Leptin
Stimulate = insulin, glucose
Rate limiting step of FA synth?
Acetyl CoA Carboxylase
Uses Biotin, CO2, ATP, Mg++
What form is Acetyl CoA Carboxylase active?
AMP activates AMPkinase that phorphorlates, and inactivates ACC. This is why AMP inhibits it, if no energy is present, body should be breaking not building things
Activators and inhibitors for Acetyl CoA Carboxylase?
Stim: citrate, insulin (dephosphorylation)
Inhib: long chain fa (palmitate, feeback inhb), Phosphorylators: epinephrine, glucagon, AMP
What do insulin, glucagon and ephinephrine do to ACC?
ACC, Acetyl CoA Carboxylase,
Insulin: dephosphorylates, activates it
Epine, Glucagon: phosphorylate, inactivate it
4 areas FA synth can be regulated?
1. ATP Citrate Lyase (frees Acetyl CoA from Oxyloacetate (phase 1)
2. Acetyl CoA Carboxylase, rate lim step (phase 2)
3. FA Synth (phase 3)
4. Desaturase enzymes
Inhibitors of ATP Citrate Lyase?
Things FA Synthase needs for it to work and make Palmitate (16:0)
(ACP) Acyl Carrier Protein, can make 2 FAs at a time
Works 7 times to make the palmitate
RXNS it does:
reduction, condensation, hydration
where does FA synth occur?
partially in mitochon. (for citrate and citrate shuttle)
What enzyme introduces double bonds to a FA?
using NADPH and oxygen,
FA lengthen ___ carbons at a time. Cleavage happens ___ at a time.
linoleic (omega 6, 18:2) and linolenic (omega 2, 18:3)
_____ lipases digest TAGs by cleaving the ____ backbone.
Where does beta oxidation of FA occur?
Mitochondria of liver, brain, adipose, kidney
What's the Carnitine shuttle
Bc VLCFAs (turned to LCFAs in peroxisome) or LCFAs cannot enter through diffusion to the mitochondria, they must be ACTIVELY transported.
4 enzymes in carnitine shuttle
1. Fatty Acyl CoA Synthetase: uses ATP, forms thioester bond with FAs and CoA,
2. CPT1: Carnitine palmitoyltransferase 1: **rate limiting step in FA degradation
3. CACT: antiporter of carnitine btwn matrix and cytosol
4. CPTII gets FA-CoA into mitorchondrial Matrix for Beta oxidation
2 parts of FA degridation
1. Carnitine shuttle
2. Beta oxidation, FAs 16-20 Cs
4 steps to beta oxidation (enzymes)
1. Acyl CoA Dehyrdrogenase, FADH2, 1.5 ATP
2. Enoyl CoA Dehydratase
3. 3-Hydoxyacyl CoA dehydrogenase, NADH, 2.5 ATP
4. Acetyl CoA Acetyltransferase (beta-keto thiolase):
Make ACETYL CoA, and 12 ATPs
For Odd #ed FA's
metab. till Propionyl-CoA, just 3 C left_steps_ turned to succinhyl CoA and sent to TCA
Where are very long chained fas metabolized?
>20 C, in peroxisomes. Once it becomes a Fatty Acyl CoA,n<20, then its sent to mitocondria for Beta oxidation
reductase remove 2x bond
isomerase moves disruptive bond
Beta oxidation in peroxisomes _____ ATP
______ converts the hydrogen peroxide into water and ___, making it less toxic
Ketone bodies are ____-soluble and ___ compounds
1. acetoacettae ---> yeilds 23 ATP
2. beta-hydorxybutyrate ---> 26 ATP
3. Acetone (makes it acidic)
Where are ketone bodies only produced?
Mitochondrial matrix of hepatocytes
What type of sport calls for ketone bodies
what utalizes ketone bodies?
muscle-fasting, marathon running
____ cannot utalize ketone bodies for energy.
___ and ___ can be cataboolized only to acetyl CoA adn acetoacetate, making them ketogenic.
Both ___ and glycosidic?
NADH, NAD+ ratios can be affected by
your feeding state
High NADH:NAD+ ratio inhibits TCA, diverts acetyl coA to ketone synth
NAD+ = starvation
How can one test for ketone bodies
acetone, glycine in urine and blood
order of steps for shortening fatty acyl CoA 2 carbons at a time
oxidation, hydration, oxidation, thiolytic cleavage