Beta Oxidation

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-OXIDATIONManoj Sigdel

-Oxidation of Fatty AcidFatty acid in body mostly oxidised by -oxidation (other types are: alpha oxidation and omega oxidation)

Oxidation of fatty acid on the carbon

Removal of 2 carbon fragment at a time; Acetyl CoA

Tissue location for oxidation Most of the tissue in the body (However, brain, erythrocytes and adrenal medulla cannot utilize fatty acids for energy requirement)

Manoj SigdelThe activity of this thiolase is very low in neurons 2) slow passage of fatty acids across the blood-brain barrier

The long-standing belief that a slow passage of fatty acids across the blood-brain barrier might be the reason. However, this has been corrected by experimental results. Otherwise, accumulated nonesterified fatty acids or their activated derivatives could exert detrimental activities on mitochondria, which might trigger the mitochondrial route of apoptosis. Here, we draw attention to three particular problems: (1) ATP generation linked to -oxidation of fatty acids demands more oxygen than glucose, thereby enhancing the risk for neurons to become hypoxic; (2) -oxidation of fatty acids generates superoxide, which, taken together with the poor anti-oxidative defense in neurons, causes severe oxidative stress; (3) the rate of ATP generation based on adipose tissue-derived fatty acids is slower than that using blood glucose as fuel. Thus, in periods of extended continuous and rapid neuronal firing, fatty acid oxidation cannot guarantee rapid ATP generation in neurons. We conjecture that the disadvantages connected with using fatty acids as fuel have created evolutionary pressure on lowering the expression of the -oxidation enzyme equipment in brain mitochondria to avoid extensive fatty acid oxidation and to favor glucose oxidation in brain.STEPS OF -OXIDATION

Activation of fatty acid occuring in cytosol.

Transport of fatty acids into mitochondria.

-Oxidation proper in mitochondrial matrix.Manoj SigdelActivation of Fatty Acid (Cytosol)

/ThiokinaseMg 2+Mg 2+3 diff thiokinase to activate; long chains (10-20), medium chain (4-12), short chain (