Fatty Acid Synth Flashcards
2nd C after carboxyl C
beta C
1st C after carboxyl C
alpha C
last C of chain (furthest from carboxyl C)
omega C
Function of fatty acids
components of triacylglycerols (energy storage) and cholesterol esters, phospholipids and sphingolipids (membranes), and precursor to eicosanoids
2 sources of FAs
diet and de novo synth in liver (palmitic acid and stearic acid-sat fat)
FA synthesis location
cytosol of liver cells
step 1 of FA synth
overall: glucose–>citrate
gluc->pyruvate>OAA and acetyl CoA–>citrate
citrate can travel….
thru mitochondrial membrane
step 2 FA synth
citrate–>acetyl CoA
NADPH formed
pyruvate metabolism occurs
in mitochondria
Sources of NADPH in FA synth
pentose phosphate pathway
malic enzyme
NADPH used as
reducing equivalents
Rate limiting step in de novo FA synth (rxn, enzyme, coenzyme)
acetyl CoA–>malonyl CoA
enzyme: acetyl CoA carboxylase
coenzyme: biotin
Regulation of RL step of de novo FA synth
thru AMP protein kinase (inhib: glucogon, act: insulin)
allosteric: inhib: palmitoyl CoA, act: citrate
Desaturation of newly synthesized FAs
double bonds can be introduced at the 9, 6, 5, or 4 carbon with 4 distinct desaturases
Elongation
occurs in ER, NADPH=reducing agent
-involves malonyl CoA, greater than 22 C chains, involved in spermatogenesis
Triacylglyceride biosynthesis
liver can use glycerol directly bc it has glycerol kinase
-triacylglyceride is packaged into VLDL in the liver or stored as fat in adipose tissue
Dietary triaglycerides are hydrolyzed in the _____ by ______.
intestine by lipases
FAs are reesterified in the
enterocyte
Triglycerides are packaged into ______ and released into _______.
chylomicrons, circulation
Lipoprotein lipase acts on
chylomicrons and VLDL
Released FAs are used for
energy by muscles and stored as triglycerides by adipose tissue