Biosynthesis of triacylglycerol

This file include these contents:
What is Triacylglycerol
Structure of triacylglycerol
Simple triacylglycerol
Mixed triacylglycerol
Biosynthesis of triacylglycerol
Utilization of triacylglycerol
Properties of triacylglycerol

1. SUBJECT: GENERAL BIOCHEMISTRY Presentation topic Biosynthesis of triacylglycerol, Utilization of triacylglycerol. Presented to : Dr.Sir Tariq Presented By Mubaika seher Bsf1800548 BS Zoology 6 th(M)

2. Contents What is Triacylglycerol Structure of triacylglycerol Simple triacylglycerol Mixed triacylglycerol Biosynthesis of triacylglycerol Utilization of triacylglycerol Properties of triacylglycerol

3. Introduction to General Biochemistry Biochemistry is the application of chemistry to the study of biological processes at the cellular and molecular level. It emerged as a distinct discipline around the beginning of the 20th century when scientists combined chemistry, physiology, and biology to investigate the chemistry of living systems . "Biochemistry has become the foundation for understanding all biological processes. It has provided explanations for the causes of many diseases in humans, animals and plants."

4. triacylglycerol A triacylglycerol (TAG) is an ester derived from glycerol and three fatty acids. Triacylglycerol  is the major form of dietary lipid in fats and oils, whether derived from plants or animals . Triacylglycerol  is composed of three fatty acids esterified to a glycerol molecule

5. triacylglycerol The fatty acid on carbon 1 is typically saturated, that on carbon 2 is typically unsaturated, and that on carbon 3 can be either .   A  triacylglycerol with three identical fatty acids is termed a simple triacylglycerol.

6. triacylglycerol The fats and oils are chemically triacylglycerol They are insoluble in water and non-polar in character and commonly known as neutral fats Structure of triacylglycerol

7. Simple triacylglycerol's Simple: contain the same type of fatty acid residue at all the three carbons e.g . tristearin

8. mixed triacylglycerol's Mixed are more common, t hey contain 2 or 3 different types of fatty acid residues. In general, F.A attached to C1 is saturated, that attached to C2 is unsaturated while on C3 can be either. Triacylglycerol of plants have higher content of unsaturated fatty acids compared to that of animals

9. Biosynthesis of Triacylglycerol's Three main pathways for triacylglycerol biosynthesis are known, sn -glycerol-3-phosphate D ihydroxyacetone phosphate pathways M onoacylglycerol pathway In maturing plant seeds and some animal tissues, a fourth pathway has been recognized in which a diacylglycerol transferees is involved. The most important route to triacylglycerol's is the  sn -glycerol-3-phosphate or  Kennedy pathway , first described by Professor Eugene Kennedy and colleagues in the 1950s, by means of which more than 90% of liver triacylglycerol's are produced.

10. Bio synthesis of triglycerides The major sites for synthesis of triglycerides are : Liver Adipose tissue Intestinal mucosa Mammary glands Muscles

11. Bio synthesis of triglycerides The intracellular site for synthesis of triglycerides is cytosol The building blocks for triglyceride synthesis are glycerol and fatty acids Both of these have to be activated before being used for triglyceride synthesis The fatty acids are activated to acyl CoA

12. Bio synthesis of triglycerides The activation reaction is catalysed by thiokinase Two high-energy bonds of ATP are utilized in the reaction

13. Bio synthesis of triglycerides Glycerol is activated by phosphorylation to glycerol-3-phosphate A high-energy phosphate of ATP is utilized in the reaction The reaction is catalysed by glycerol kinase

14. Most tissues possess glycerol kinase and can use glycerol for triglyceride synthesis However, adipose tissue lacks glycerol kinase It cannot utilize the glycerol released from hydrolysis of triglycerides In adipose tissue, glycerol-3-phosphate is formed from dihydroxyacetone phosphate Dihydroxyacetone phosphate is formed from glucose in the glycolytic pathway This is reduced to glycerol-3-phosphate in adipocytes

15. Glycerol-3-phosphate is acylated at position 1 The reaction is catalysed by glycerol-3- phosphate acyl transferase The product of the reaction is 1-acylglycerol-3-phosphate

16. An acyl group is added at position 2 to form 1,2-diacylglycerol-3-phosphate 1,2-Diacylglycerol-3-phosphate is also known as phosphatidic acid

17. Phosphatidic acid phosphatase splits off the phosphate group 1,2-Diacylglycerol-3-phosphate is converted into 1,2-diacylglycerol

18. An acyl group is added at position 3 by diacylglycerol acyl transferase Diacylglycerol is converted into triacylglycerol (triglyceride)

19. Intestinal mucosa uses monoacylglycerol to initiate triglyceride synthesis 2-Monoacylglycerol is formed in intestine during digestion of triglycerides This is absorbed and is reused for triglyceride synthesis

20. Utilization of triacylglycerol. They are primarily intermediate products of triacylglycerol digestion, clearance from the bloodstream, or intracellular metabolism. They are used as emulsifiers in processed food. Once consumed, triacylglycerol is hydrolyzed into free fatty acids and monoglycerides in the small intestine prior to absorption.

21. Utilization of triacylglycerol. Oils in the form of triacylglycerol's are the most abundant energy-dense storage compounds in eukaryotes, and their metabolism plays a key role in cellular energy balance, lipid homeostasis, growth, and maintenance. Plants accumulate oils primarily in seeds and fruits. Plant oils are used for food and feed and, increasingly, as feedstock's for biodiesel and industrial chemicals. Although plant vegetative tissues do not accumulate significant levels of triacylglycerol's, they possess a high capacity for their synthesis, storage, and metabolism. The development of plants that accumulate oil in vegetative tissues presents an opportunity for expanded production of triacylglycerol's as a renewable and sustainable bioenergy source

22. Utilization of triacylglycerol. The energy-giving nutrients are carbohydrates, lipids and proteins Lipids are a concentrated source of energy Their calorific value is much more than that of carbohydrates and proteins Human beings have a limited capacity to store carbohydrates and proteins Moreover , a significant amount of water is required to store them In an average person, about 80% of the stored energy is in the form of lipids

23. Contind … In an average person, about 80% of the stored energy is in the form of lipids The lipids are stored mostly in the form of triglycerides ( triacylglycerols ) A triglyceride consists of three fatty acids esterified with a molecule of glycerol All the cells store some amount of triglycerides But adipose tissue is the major site for storage of triglycerides Adipose tissue is rich in adipocytes (fat cells)

24. Contind … Adipocytes store triglycerides in the form of fat globules Most of the space in adipocytes may be filled up with triglycerides Adipocytes can synthesize as well as hydrolyse triglycerides Adipose tissue takes up fatty acids from circulation These may be of dietary or endogenous origin Adipose tissue converts them into triglycerides When fatty acids are required, the stored triglycerides are hydrolysed Adipose tissue releases the fatty acids in plasma Glycerol is also released as adipocytes cannot re-utilize it

25. Properties of triacylglycerol Chemical Properties Hydrolysis Hydrogenation: Saponification Halogenation Rancidity

26.  Hydrolysis: Triglycerides (fats) can be hydrolyzed to produce glycerol and fatty acids in the presence of acid and heat or with a suitable lipase enzyme under biological conditions.

27. Hydrogenation: Hydrogenation is a process of adding hydrogen atoms to unsaturated fats until they become saturated. Hydrogenation of fat is a process used in industries, food manufacturers, to synthesize modified plant fats called hydrogenated fats that share similar texture and taste characteristics with saturated animal fats.

28. Saponification: The process of hydrolysis of fat by aqueous alkali ( NaOH or KOH) to yield glycerol and the salt of fatty acid (soap) is called saponification or alkaline hydrolysis of esters. Soaps are sodium or potassium salts of long chain fatty acids.

29. Halogenation: Unsaturated fatty acids have the ability to bind halogens like Cl 2 , Br 2  and I 2  to their double bonds. It is a very important property which determines the degree of unsaturation of the fat or oil that determines its biological value.

30. Rancidity: Rancidity is a term generally used to denote unpleasant odors and flavors in foods resulting from deterioration in the fat or oil portion of a food. The triacylglycerol's in fats with low molecular mass carboxylic acids undergo oxidation very quickly when exposed to air, moisture and light or hydrolyzed in the presence of bacterial lipases.

31. References Biochemistry. ( n.d. ). Retrieved from McGill: https://www.mcgill.ca/biochemistry/about-us/information/biochemistry Biosynthesis of Triacylglycerols . ( n.d. ). Retrieved from The Lipid Web: https://www.lipidmaps.org/resources/lipidweb/lipidweb_html/lipids/simple/tag2/index.htm#:~:text=Biosynthesis%20of%20Triacylglycerols,monoacylglycerol%20pathway%20in%20the%20intestines. Shanklin , C. X. ( n.d. ). Triacylglycerol Metabolism . Retrieved from https://www.annualreviews.org/: https://www.annualreviews.org/doi/pdf/10.1146/annurev-arplant-043015-111641 Ahmad, A. ( n.d. ). triacylglycerol . Retrieved from https://www.slideshare.net/AshfaqAhmad52/triacylglycerol Biosynthesis of triacylglycerol . ( n.d. ). Retrieved from Slidesshare : https://www.slideshare.net/RajeshChaudhary10/tag-biosynthesis-storage-and-functions