β- Oxidation of fatty acid

β- Oxidation of fatty acid:

β- Oxidation may be defined as the oxidation of fatty acids on the β -carbon atom, this results in the removal of a two carbon fragments of acetyl Co-A and acyl Co-A.

1. Activation of fatty acid:

Long chain fatty acids activated to fatty acyl Co-a by the enzyme thiokinase where ATP splits to AMP and

PP (Pyrophosphate) in prescience of enzyme A and Mg +2

2. Transport of acyl-Co-A in to mitochondria (Carnitine transport system):

The inner mitochondria membrane is impermeable to fatty acids. A specialized carrier system operates to transport activated fatty acid from cytosol to the mitochondria.  This occurs in four steps:

3. β- Oxidation:

Energetics of β- Oxidation (Palmitic acid): 

Mechanism:

1. β- Oxidation (7 cycles)

2 FAH2 [oxidized by ETC, each FAH2 H gives 2ATP]: 14

7 NADH [oxidized by ETC, each NAH gives 3ATP]    : 21

 

2.    Form 8 Acetyl-CoA

Oxidized by citric acid cycle, each 8 x12 =                    96

Total energy from one male of palmityl-CoA =            131

Energy utilized for formation of palmityl-CoA =           02

Net yield of oxidation of one male of Palmitate =       129

 

The bio synthesis of fatty acid takes place in two phases.

1.  Malonyl CoA formation.

Acetyl-CoA reacts with CO2 in the presence of ATP to form malonyl- CoA with the help of an enzyme acetyl- CoA carboxylase.

2. Fatty acid synthatase complexreactions.

The multi enzyme complex known as fatty acid synthatase (FAS) take place in the fatty acid synthesis FAS complex consist of two similar subunits (Dimer). Each monomer subunit consists an acyl carrier protein (ACP) attached with its 4-phasphontheine group.

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