Fatty Acid Spiral:
The fatty acid-CoA molecule is degraded into acetyl CoA molecules
by a recurring cyclic sequence of four reactions. The end product
of each cycle is the fatty acid shortened by 2 carbons and acetyl
The series of reactions is also known as the beta-oxidation
pathway because the major reaction site is the beta-carbon or
#3 carbon from the thioester carbon. The complete reaction sequence
for one fatty acid cycle is given as follows.
Actually, the reactions in the fatty acid cycle closely
resemble the last three steps of the citric acid cycle.
Step 1: Oxidation (Dehydrogenation)
The coenzyme FAD, which is directly connected to the electron
transport chain is involved with this reaction. Again it is somewhat
unusual for hydrogens to be removed from an alkane hydrocarbon
The hydrogens on the #2 and # 3 carbons are removed to form
a trans double bond (alkene) type compound. The FAD is converted
FADH2 and carries the two hydrogens and two electrons
in the electron transport chain.
Because this is the second enzyme complex, the net yield of ATP
Palmityl-2-ene CoA- Chime
in new window
Link to Chime: Acyl-CoA
Dehydrogenase - Department of Biochemistry,The University