chemistry-lesson.pptx
- 1. Beta oxidation with even and odd number of carbon atoms and their regulation Name : Neha University roll no. : 20025569011 Submitted to : Dr.vandana k.singh Bsc Hons zoology (2nd year)
- 2. Contents • Defination • Oxidation of fatty acid • Activation • Transportation • Beta oxidation pathway • Oxidation of odd chain fatty acid • Regulation • Research paper summary • refrences
- 3. Defination The repetitive four-step process, called - oxidation, by which fatty acids are converted into acetyl- CoA
- 4. Oxidation of fatty acid • Mitochondrial oxidation of fatty acids takes place in three stages. • In the first stage Oxidation—fatty acids undergo oxidative removal of successive two- carbon units in the form of acetyl-CoA, starting from the carboxyl end of the fatty acyl chain. • In the second stage of fatty acid oxidation, the acetyl groups of acetyl-CoA are oxidized to CO2 in the citric acid cycle, which also takes place in the mitochondrial matrix. Acetyl-CoA derived from fatty acids thus enters a final common pathway of oxidation with the acetyl- CoA derived from glucose via glycolysis and pyruvate oxidation. • in the third stage donate electrons to the mitochondrial respiratory chain, through which the electrons pass to oxygen with the concomitant phos-phorylation of ADP to ATP
- 5. • Stage 1: A long-chain fatty acid is oxidized to yield acetyl residues in the form of acetyl-CoA. This process is called oxidation. • Stage 2: The acetyl groups are oxidized to CO2 via the citric acid cycle. • Stage 3: Electrons derived from the oxida-tions of stages 1 and 2 pass to O2 via the mitochondrial respiratory chain, providing the energy for ATP synthesis by oxidative phosphorylation.
- 6. Activation • Fatty acid breakdown occurs in the cytosol of prokaryotes, in peroxisomes in plants and in the mitochondrial matrix of all other eukaryotes. • Before entering the mitochondrial matrix, the fatty acid is activated by forming a thioester link with CoA . • This reaction is catalyzed by acyl CoA synthetase (also called fatty acid thiokinase), which is present on the outer mitochondrial membrane, and uses a molecule of ATP. • The overall reaction is irreversible due to the subsequent hydrolysis of PPi to two molecules of Pi
- 7. Transport into mitochondria The inner mitochondrial membrane is impermeable to fatty acids and a specialized carnitine carrier system operates to transport activated fatty acids from cytosol to mitochondria. Once activated, the acyl CoA is transported into the mitochondrial matrix.
- 8. Beta oxidation pathway 1. Oxidation of the fatty acyl CoA to enoyl CoA forming a trans double bond on the fatty acyl chain and producing FADH2 (catalyzed by acyl CoA dehydrogenase). 2. Hydration of the transenoyl CoA to form beta-hydroxyacyl CoA (catalyzed by enoyl CoA hydratase). 3. Oxidation of beta-hydroxyacyl CoA to Beta- ketoacyl CoA producing NADH (catalyzed by hydroxyacyl CoA dehydrogenase). 4. Cleavage, or thiolysis, of beta-ketoacyl CoA by a second CoA molecule, giving acetyl CoA and an acyl CoA shortened by two carbon atoms (catalyzed by b-ketothiolase).
- 9. Six more passes through the pathway yield seven more molecules of acetyl- CoA, the seventh arising from the last two carbon atoms of the 16-carbon chain. Eight molecules of acetyl-CoA are formed in all. Beta oxidation pathway
- 10. Complete Oxidation of Odd- Number Fatty Acids Requires Three Extra Reactions Oxidation of propionyl-CoA produced by -oxidation of odd-number fatty acids. The sequence involves the carboxylation of propionyl-CoA to D- methylmalonyl-CoA and conversion of the latter to succinyl-CoA. This conversion requires epimerization of D- to L-methyl-malonyl-CoA, followed by a remarkable reaction in which substituents on adjacent carbon atoms exchange positions
- 11. • The major point of control of beta oxidation is the availability of fatty acids. • The major source of free fatty acids in the blood is from the breakdown of triacylglycerol stores in adipose tissue, which is regulated by the action of hormone-sensitive triacylglycerol lipase . • Fatty acid breakdown and fatty acid synthesis are coordinately controlled to prevent a futile cycle . Regulation
- 13. Summary • Mitochondrial fatty acid β-oxidation disorders (FAODs) are a heterogeneous group of defects in fatty acid transport and mitochondrial β-oxidation. • They are inherited as autosomal recessive disorders and have a wide range of clinical presentations. • The background information and case report provide important insight into mitochondrial FAODs. • The article provides a wealth of information describing the scope of these disorders. • This article presents a typical case of medium chain acyl-CoA dehydrogenase deficiency and summarizes the pathophysiology, clinical presentation, diagnosis and treatment of mitochondrial FAODs.
- 14. Quiz Question:1 Where are the enzyme for beta-oxidation present ? (a) Nucleus (b) Cytosol (c) Mitochondria (d) Golgi apparatus Question:2 which one of following is an essential fatty acid ? (a) Linolenic acid (b) Palmitic acid (c) Linoleic acid (d) Both(a) & (b) Question:3 The long chain fatty acids get transported through the inner mitochondrial membrane (a) as acyl-CoA derivative (b) Freely (c) As carnitine derivative (d) Require sodium dependent carrier
- 15. Question : 4 where do the long chain fatty acid gets first activated ? (a) Microsomes (b) mitochondria (c) Cytosol (d) Nucleus Question:5 which of the following is a saturated fatty acid ? (a) Linoleic acid (b) Erucic acid (c) Palmitic acid (d) Oleic acid
- 16. References • Lehninger principles of biochemistry • Khan academy
- 17. Thanks