Beta-oxidation of fatty acids

1. DEPARTMENT OF BIOCHEMISTRY
LUMBINI MEDICAL COLLEGE
PRAVAS, TANSEN, NEPAL

2. Fatty acids oxidation( beta-oxidation):-
 It involves three steps:
a) Activation of fatty acids( Cytosol).
b) Transport of Acyl CoA from cytosol to mitochondria.
c) Beta-oxidation proper( Mitochondrial Matrx).

3. a) Activation of fatty acids:-
site = Cytosol
Acyl Co-A Synthase
Free fatty acids Fatty acyl Co-A
+
Co-A ATP AMP + PPi
Ppi Pyrophosphatase 2 Molecule of inorganic phosphate
H2O

4. b) Transport of fatty acid ( Acyl CoA) From Cytosol
to mitochondria:-
fig:-

5. Carnitine:-
 Carnitine is synthesized in liver and kidney.
 It require Lysin and metheonine for it’s synthesis.
 A large conc. Is present in skeletal muscle.
Diet Synthesized in the body
Source
malonyl CoA inhibitors Carnitine
Functions
Transport of Acyl CoA from cytosol to mitochondria

6. c) Beta-oxidation proper in mitochondrial matrix:
Site = Matrix of mitochondria
a) Oxidation of even chain fatty acid:
Acyl Co-A
Acyl CoA DH FAD
FADH2
Enoyl Co-A
Enoyl CoA hydratase H2O
Beta hydroxy acyl CoA

7. Beta hydroxy acyl CoA
beta OH acyl CoA NAD
NADH2
Beta-keto acyl Co-A
Thiolase CoA
Acetyl CoA
Acyl CoA
Note:-
a) Short Chain fatty acid No need carnitine
b) Medium chain fatty acid
c) Long chain fatty acid. Need carnitine

8. Energetic of palmitic acid condition
 Palmitic acid contain 16 carbon molecules.
 It undergoes 7 cycles to be completely oxidised and
produced energy.
 8 molecules of acetyl CoA produced in whole 7 cycle.
 Total energy are given below:

9. Mechanism No. of ATP
produced lost
1) In One Cycle:-
FADH2 produced = 2 ATP
NADH2 produced = 3 ATP
5 ATP
So, In 7 cycles 7 X 5 = 35 ATP’s
2) No. of acetyl CoA produced
in 7 cycles is 8:
: 1 Acetyl CoA = 12 ATP
: 8 Acetyl CoA produced 8X12= 96 ATP
3)During Activation of fatty acid
the energy utilized 2ATP

10. :- Total ATP’s produced = 35+96 =131 ATP’s
and utilized(lost) = 2 ATP’s
:- Net yeild of ATP’s after complete
oxidation of palmitic acid (131 – 2) = 129 ATP’s

11. Disorders:-
1) Carnitine deficiency:
 It happens due to immature liver, kidney functions are not normal
and occurs incase of pre-term newborns.
 During pregnancy, trauma, burns, requirement of carnitine is
increased and body can’t compensate for that.
 During hemodialysis, large amount of carnitine is filtered out.

12. 2) Sudden infants death syndrome :-
 Infants die on bed usually during night.
 Decreased glucose = utilized with in 2 hrs
beta-oxidation ( normally happen)
 Deficiency of medium chain Acyl-CoA dehydrogenase
No Beta-oxidation
No Acetyl CoA
No ATP
Gluconeogenesis Hypoglycemia Death