Fatty acid β-oxidation is the process by which fatty acids are broken down to produce energy. Fatty acids primarily enter a cell via fatty acid protein transporters on the cell surface. Once inside, FACS adds a CoA group to the fatty acid. CPT1 then converts the long-chain acyl-CoA to long-chain acylcarnitine.

1. PRESENTED BY:
EVELIN GEORGE
2ND BIOCHEMISTRY
BETA OXIDATION OF
FATTY ACIDS
PRESENTED BY:
EVELIN GEORGE
2ND B.Sc. BIOCHEMISTRY

2. FATTY ACID
STRUCTURE

3. BETA OXIDATION
 Beta oxidation may be defined as the oxidation of fatty acids on
the beta carbon atom.
 More specifically, beta oxidation consists in breaking down
long fatty acids that have been converted to acyl-CoA chains into
progressively smaller fatty acyl-CoA chains.
 Beta oxidation goes on until two acetyl-CoA molecules are
produced and the acyl-CoA chain has been completely broken
down.
 In eukaryotic cells, beta oxidation takes place in the mitochondria,
whereas in prokaryotic cells, it happens in the cytosol.

4.  Activation of fatty acids- in the cytosol
 Transport of fatty acids into mitochondria.
 Beta-Oxidation in the mitochondrial matrix [fatty
acids are oxidised by most of the tissues in the
body].
 Brain, erythrocytes and adrenal medulla cannot
utilise fatty acids for energy requirement.
steps

5. *
*Fatty acid activation takes places in the cytoplasm.
*Fatty acids are activated to acyl CoA by thiokinases
or acyl CoA synthetases.
*This reaction occurs in 2 steps and requires ATP,
coenzymes A and Mg2+.
*Fatty acid reacts with ATP to form acyladenylate
which then combines with coenzymes to produce
acyl CoA.
*Two high energy phosphates are utilized, as ATP is
converted to pyrophosphate[PPi].

6. The inner mitiochondrial membrane is
impermeable to fatty acids.A specialized
carnitine carrier system [carnitine shuttle]
operates to transport activated fatty acids
from cytosol to the mitochondria.
Transport occurs in 4 stages
Acyl group of acyl CoA is transfrred to
carnitine catalysed by carnitine
acyltransferase1 [CAT-1], present on the
outer surface of the inner mitochondral
membrane.

7. The acyl-carnitine is transported
across the membrane to mitochondrial
matrix by a specific carrier protein
[Translocase].
 Carnitine acyltransferase-2 [CAT-2],
Found on the inner mitichondrial
membrane, which converts acyl-
carnitine to acyl CoA.
The carnitine released returns to
cytosol for reuse by translocase.

8. Each cycle of beta oxidation, liberating a two
carbon unit-acetyl CoA, occurs in a sequence
of four reaction
1.OXIDATION
Acyl CoA undergoes dehydrogenation by an FAD-
dependent flavoenzyme, acyl CoA dehydrogenase.
A double bond is formed between alpha and beta
carbon [ 2 and 3 carbon]
2,HYDRATION
Enoyl CoA hydratase brings about the hydration
of the double bond to form beta hydroxyacyl CoA.
*

9. 3.OXIDATION
*Beta- hydroxylacyl CoA dehydrogenase catalyses
the second oxidation and generates NADH. The
product formed is beta-ketoacyl CoA.
4.CLEVAGE
*The final step is the liberation of a 2 carbon
fragment, acetyl CoA from acyl CoA,
*This occurs by a thiolytic cleavage cataysed by
beta ketoacyl CoA thiolase or thiolase.
*The new acyl CoA, containing two carbons less
than the original, reenters the beta oxidation cycle.
The process continues till the fatty acid is
completely oxidised,

10. OVERALL
REACTION.