Flashcards in Fatty Acid and TAG Metabolism Deck (52)
which two fatty acids cannot synthesize double bonds beyond the 9 Carbon position?
How must we obtain linoleic acid and alpha-linolenic acid?
what makes arachidonic acid?
what is the parent of all eicosanoids?
arachidonic acid (from linoleic acid)
When is fatty acid synthesis and TAG synthesis most likely to occur?
during fed state
what hormone promotes TAG and fatty acid synthesis?
what is the prepretory step in fatty acid synthesis?
acetyl CoA is superactivated/prepped by making malonyl CoA
where are the enzymes of FA synthesis located?
what does malic enzyme convert malate directly to?
pyruvate and removes CO2 and produces NADPH
what does acetyl CoA carboxylsae (ACC) need?
CO2 and biotin
what does citrate do the ACC?
activates allosterically (Short term)
what does palmitoyl CoA do to ACC?
allosterically inhibits ACC
what does phosphorylation on Ser/Thr residues through AMPK do to ACC?
inhibits ACC (hormonally)
what causes phosphorylation of ACC?
glucagon / epinepherine
when is ACC active?
what does insulin activate to make ACC active?
FAS takes 1 malonyl CoA and adds how many carbons to it?
what are the two forms of FAS?
how much energy is needed to synthesize FA?
7 ATP - to prep malonyl CoA
14 NADPHs - elongation steps
what determines the overall rate of FA synthesis?
availability of malonyl CoA
what energy source is important during elongation steps?
Every 2 C added in FA synthesis are added in the form of what?
malonyl CoA - uses 2 out of the 3 C (1 C gets kicked off)
what are the 2 major roles of citrate?
allosteric activator of ACC
vehicle by which acetyl coA moves from mitochondria to cytoplasm
what moves acetyl CoA from mitochondria to cytoplasm?
where does chain elongation and desaturation occur?
what 3 things do you need for the desaturation of FA?
3. cytochrome B5 reductase + NADPH
what does elongation and desaturation allow us to do?
synthesize polysaturated FA from essentail FA
what stimulates TAG synthesis from FA?
what stimulates glycogen synthesis from glucose?
which part of TAGs is essential for its storage?
which tissues have glycerol phosphate?
what are 90% of FA in plasmas as?
fatty acid esters (TAGS, cholsteryl esters, phospholipids) in circulating lipoproteins
where does unsaturated FA have double bonds?
3 C apart
what introduces the kinks to unsaturated FA?
if linoleic acid is not supplied what becomes essential in diet?
what are the precursors of FA synthesis?
acetyl CoA (pantothenic acid)
what is a key intermediate between fat and carb metabolism?
what are the 3 pathways of FA synthesis?
1.synthesis of palmitate from Acetyl CoA
2.elongation of palmitate
where is acetyl CoA in mitochondria coming from?
oxidation of pyruvate (PDH complex)
what does high ATP in the mitochondria inhibit?
what is the first committed step of FA synthesis?
Acetyl CoA carboxylase (ACC)
what is the rate limiting enzyme for FA synthesis?
what does the carboxylation of acetyl CoA to form malonyl CoA require as far as energy?
1 ATP per malonyl CoA formed!
what are long term regulation of ACC that promote FA synthesis?
high carb and fat free diets - upregulation, induction
what are long term regulation of ACC that decrease FA synthesis?
high fat diets, fasting, glucagon - down reg, repression
what up regulates the amount of dimeric form of FAS expressed?
what are the key regulators of Acetyl CoA carboxylase (ACC)?
palmitoyl CoA/fatty acyl CoA
where does FA elongation occur by reversal of Beta oxidation?
mitochondria (minor elongation pathway)
where is the major elongation pathway taking place?
what are sites of unsaturation introduced to?
fatty acyl CoA desaturases that introduce double bonds to 5,6,9 position
what are the essential FA?
*they have unsaturations beyond the 9 carbon