Fatty acid oxidation Types of fatty acid oxidation Overview of fatty acid oxidation Beta-Oxidation of fatty acid Steps in Beta-Oxidation of fatty acid Stoichiometry of Beta oxidation Reference

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Beta oxidation of saturated fatty acid
Presentation report by
IPSITA SAHOO
Registration No – 200705180160
DEPARTMENT OF ZOOLOGY
Under the supervision of
Dr. Sitaram swain
Assistant Professor, School of Applied Sciences
Centurion University of Technology and Management, Bhubaneswar, Odisha
SCHOOL OF APPLIED SCIENCES (SOAS)
Centurion University of Technology and Management, Bhubaneswar, Odisha

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CONTENTS
Fatty acid oxidation
Types of fatty acid oxidation
Overview of fatty acid oxidation
Beta-Oxidation of fatty acid
Steps in Beta-Oxidation of fatty acid
Stoichiometry of Beta oxidation
Reference

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Introduction
Fatty acid oxidation
 Fatty acid contains a long hydrocarbon chain and a terminal carboxylate group.
 The hydrocarbon chain may be saturated (with no double bond) or may be
unsaturated (containing double bond).
 Fatty acid Oxidation is the process where energy is produced by degradation of
fatty acids.
Types of fatty acid oxidation
Beta-Oxidation of fatty acid
 Beta-Oxidation may be defined as the oxidation of fatty acids on the beta-carbon
atom.
 This results in the sequential removal of a two carbon fragment, acetyl CoA.
 Occurs in the mitochondria and strictly aerobic.
 After production Acetyl-CoA is fed directly into the Krebs cycle.
 It occurs in many tissues including liver, kidney and heart.
 Fatty acids oxidation doesn't occur in the brain.
• Major mechanism, occurs in themitochondria matrix.
• 2-C units are released asacetyl CoA per cycle
Beta oxidation
• Predominantly takes place inbrain and liver,
• one carbon is lost in the form ofCO2 per cycle
Alpha
oxidation
• Minor mechanism, but becomes important in conditions
of impaired beta oxidation
Omega
oxidation

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Steps in Beta-Oxidation of fatty acid
Steps -1; Activation of fatty acid
Steps -2; Transport of fatty acid into mitochondria
 The inner mitochondrial membrane is impermeable to fatty acids.
 A specialized carnitine carrier system (carnitine shuttle) operates to transport
activated fatty acids from cytosol to the mitochondria.
 Fatty acids are activated to acyl CoA by
thiokinases or acyl CoA synthetases.
 The reaction occurs in two steps and
requires ATP, coenzyme A and Mg2+
 Fatty acid reacts with ATP to form
acyladenylate which then combines with
coenzyme A to produce acyl CoA.
 Two high energy phosphates are utilized,
since ATP is converted to pyrophosphate
(PPi).
 The enzyme inorganic pyrophosphafase
hydrolyses PPi to phosphate.
 The immediate elimination of PPi makes
this reaction totally irreversible.

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 This occurs in four steps
1. Acyl group of acyl CoA is transferred to carnitine (β-hydroxy γ-trimethyl
aminobutyrate) catalyzed by carnitine acyltransferase (CAT) (present on the
outer surface of inner mitochondrial membrane).
2. The acyl-carnitine is transported across the membrane to mitochondrial matrix by
a specific carrier protein.
3. Carnitine acyl transferase ll (found on the inner surface of inner mitochondrial
membrane) converts acyl-carnitine to acyl CoA.
4. The carnitine released returns to cytosol for reuse.
Steps -3; Beta-Oxidation proper
 Each cycle of β -oxidation, liberating a two carbon unit-acetyl CoA, occurs in a
sequence of four reactions
1. Oxidation
2. Hydration
3. Oxidation
4. Cleavage.
1. Oxidation
• Acyl CoA undergoes dehydrogenation by an FAD-dependent flavoenzyme, acyl
CoA dehydrogenase.
• A double bond is formed between α and β carbons (i.e., 2 and 3 carbons)

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2. Hydration
• Enoyl CoA hydratase brings about the hydration of the double bond to form 3 -
hydroxyacyl CoA.
3. Oxidation
• 3-Hydroxyacyl CoA dehydrogenase catalyses the second oxidation and
generates NADH.
• The product formed is β-ketoacyl CoA.
4. Cleavage
• The final reaction in β -oxidation is the liberation of a 2 carbon fragment, acetyl
CoA from acyl CoA.
• This occurs by a thiolytic cleavage catalysed by β-ketoacyl CoA thiolase (or
thiolase).
 The new acyl CoA, containing two carbons less than the original, reenters the β-
oxidation cycle.
 The process continues till the fatty acid is completely oxidized.

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Stoichiometry of Beta oxidation
Beta-Oxidation of palmitate (16 carbons)
Palmitoyl-CoA+ 7 CoA+ 7 FAD+ 7 NAD+
+7H20  8 acetyl-CoA+ 7 FADH2+ 7
NADH
Acetyl-CoA is catabolized via TCA cycle, and FADH2 and NADH transfer electrons to
the electron transport chain. Thus, we can easily compute the metabolic energy yield
fatty acid oxidation in terms of moles of ATP synthesized.
Reaction ATP yield ATP consumed
Activation of palmitate to
palmitoyl-CoA
-2
Oxidation of 8 acetyl-CoA 8*10 = 80
Oxidation of 7 FADH 7*1.5 = 10.5
Oxidation of 7 NADH 7*2.5 = 17.5
Net: Palmitate 16 Co2+ 130 H2O 180 - 2 = 106
These calculations assume that mitochondrial oxidative phosphorylation produces 1.5
ATP per FADH2 oxidized and 2.5 ATP per NADH oxidized.

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References
 Cox, Michael M., and David L. Nelson.(2008) Lehninger principles of
biochemistry. Vol. 5. New York: Wh Freeman.
 Pranav, K., & Mina, U. (2013). Life Sciences: Fundamentals and practice. New
Delhi: Pathfinder Academy.
 Satyanarayana, U. (2014). Metabolism of lipids.
Acknowledgements
• My subject teacher: Dr. Sitaram swain
• Dr. Yashaswi Nayak, HoD and Dean SoAS
• All the Faculty members of Department of Zoology, School of Applied sciences,
CUTM
• Family and friends