Recommended
More Related Content
What's hot
What's hot (19)
Similar to BIOCHEMISTRY
Similar to BIOCHEMISTRY (20)
Recently uploaded
Recently uploaded (20)
BIOCHEMISTRY
- 1. LIPIDS SUBMITTED BY:- NEHA AGRAWAL M.Sc. 1St Sem.
- 2. Lipids Biological roles of lipids Structure and properties of storage lipids Structure and properties of membrane lipids Structure and properties of signaling lipids Methods of Lipid Structure Determination Learning Goals: Know: EOC Problem 1 starts off with “what is a lipid” see next slide for the diversity of lipids.
- 3. Lipids: Structurally Diverse Class Organic molecules that are characterized by low solubility in water, that is, are relatively hydrophobic. Thought question: would some amino acids act like lipids ? …consider I, L, F, W, Y
- 4. Biological Functions of Lipids Storage of energy Reduced compounds: lots of available energy Hydrophobic nature: good packing Insulation from environment Low thermal conductivity High heat capacity (can “absorb” heat) Mechanical protection (can absorb shocks) Water repellant Hydrophobic nature: keeps surface of the organism dry Prevents excessive wetting (birds) Prevents loss of water via evaporation Buoyancy control and acoustics in marine mammals Increased density while diving deep helps sinking (just a hypothesis) Spermaceti organ may focus sound energy: sound stun gun?
- 5. More Functions Membrane structure Main structure of cell membranes Cofactors for enzymes Vitamin K: blood clot formation Coenzyme Q: ATP synthesis in mitochondria Signaling molecules Paracrine hormones (act locally) Steroid hormones (act body-wide) Growth factors Vitamins A and D (hormone precursors) Pigments Color of tomatoes, carrots, pumpkins, some birds Antioxidants Vitamin E
- 7. Effect of cis – unsaturation on Stearic Acid 18:0 EOC Problem 8: Draw the structure of omega-6 fatty acid 16:1. You can pause here and do it !
- 8. Fatty Acids
- 9. Go Back to the Table…Look at Melting Points + Their Meaning EOC Problem 2a and 2c Get Into Melting Points and
- 10. Glycerol = Heart of Some Complex Lipids
- 11. Triacylglycerol When Unsat’d acids are there, they are first
- 14. Sperm Whales – Fatheads of the Deep Adjusts buoyancy with Deep dives (1000m deep) by crystallizing and becoming denser…less energy is used by the whale (to overcome buoyancy).
- 15. Saturated and Unsaturated Fats in Food Lipids
- 16. Trans Fatty Acids Trans fatty acids form by partial dehydrogenation of unsaturated fatty acids Done to increase shelf life or stability at high temperature of oils used in cooking (especially deep frying) A trans double bond allows a given fatty acid to adopt an extended conformation Trans fatty acids can pack more regularly and show higher melting points than cis forms Consuming trans fats increases risk of cardiovascular disease Avoid deep-frying partially hydrogenated vegetable oils Current trend: reduce trans fats in foods (Wendy’s, KFC) EOC Problem 9: Calalytic hydrogenation of Veggie Oils
- 18. Wax
- 19. Ear Wax (Cerumen) is Not Wax The primary components of ear wax are shed layers of skin: 60% of the earwax consisting of keratin 12–20% saturated and unsaturated long-chain fatty acids, alcohols and squalene, 6–9% cholesterol
- 20. Major Types of Lipids
- 21. What “X” Can Be: Why are these arrows here? 5th Edition
- 22. 6th Edition
- 23. Phosphatidylcholine • Phosphatidylcholine is the major component of most eukaryotic cell membranes • Many prokaryotes, including E. coli, cannot synthesize this lipid; their membranes do not contain phosphatidylcholine
- 24. Phosphatidyl Inositol – Membrane Signaling
- 25. Phospholipases
- 26. Ether Lipids: Plasmalogen Vinyl ether analog of phosphatidylethanolamine Common in vertebrate heart tissue Also found in some protozoa and anaerobic bacteria Function is not well understood Resistant to cleavage by common lipases but cleaved by few specific lipases Increase membrane rigidity? Sources of signaling lipids? May be antioxidants?
- 27. High concentration in Heart Lipids Two Ether Linked aliphatic groups Active at 10-9 M … Part of many things including Inflammation
- 28. Galactolipids – in Chloroplasts 70-80% of Lipids in Thylakoid Membranes
- 29. One Type of Achaea Membrane Lipid in Hyperthermophiles
- 32. Neuraminic Acid = Sialic Acid
- 33. Shapes of these Phospholipids
- 35. ABO Blood Group Substances, 5th Ed
- 37. Membrane Lipid as Progenitor to Prostaglandins - 1 Arachidonic Acid C20:4Δ5,8,11,14
- 38. Eicosanoids Asprin and Ibuprofin Inhibit Synthesis of Prostaglandins + Thromboxanes NSAID’s = Non Steroid Anti Inflammatory Drugs Hormones Part of Blood Clotting Smooth Muscle Contraction
- 39. Cholesterol – Steroid (= 4 fused rings)
- 40. Steroid Hormones Made from Cholesterol Cholesterol Multistep Glucose Metabolism Salt Excretion Anti-inflammatory
- 42. A child who began life in a closet
- 43. Retinal Comes from Carotene
- 45. Mitochondrial and Chloroplast Membrane Electron Carriers
- 46. Carotenoids
- 49. Gas or HPLC to separate and identify the Fatty Acid Methyl Esters
- 50. Mass Spectrometry of a Lipid
- 51. A Little Review
- 52. Things to Know and Do Before Class 1. Fatty acid properties and system of names. 2. Structures of Triacylglycerols. 3. Structures of Glycerol-Phospho-lipids. 4. Structures of Sphingolipids. 5. Progenitor of prostaglandins, thromboxanes, and leukotrienes: arachidonic acid. 6. Cholesterol and other steroids. 7. Analysis of lipids. 8. Know how to do EOC Problems: 1, 2a and c, 7- 13 and for fun (if you cook) problem 3 (works the same for Hollandaise sauce).
Editor's Notes
- FIGURE 10–2a The packing of fatty acids into stable aggregates. The extent of packing depends on the degree of saturation. (a) Two representations of the fully saturated acid stearic acid, 18:0 (stearate at pH 7), in its usual extended conformation. FIGURE 10–3 Glycerol and a triacylglycerol. The mixed triacylglycerol shown here has three different fatty acids attached to the glycerol backbone. When glycerol has different fatty acids at C-1 and C-3, C-2 is a chiral center (p. 17). FIGURE 10–9 (part 1) Glycerophospholipids. The common glycerophospholipids are diacylglycerols linked to head-group alcohols through a phosphodiester bond. Phosphatidic acid, a phosphomonoester, is the parent compound. Each derivative is named for the head-group alcohol (X), with the prefix “phosphatidyl-.” In cardiolipin, two phosphatidic acids share a single glycerol (R1 and R2 are fatty acyl groups). *Note that the phosphate esters in phosphatidylinositol 4,5-bisphosphate each have a charge of about -1.5; one of their —OH groups is only partially ionized at pH 7. FIGURE 10–17 Cholesterol. In this chemical structure of cholesterol, the rings are labeled A through D to simplify reference to derivatives of the steroid nucleus; the carbon atoms are numbered in blue. The C-3 hydroxyl group (shaded blue) is the polar head group. For storage and transport of the sterol, this hydroxyl group condenses with a fatty acid to form a sterol ester. FIGURE 10–22d Some other biologically active isoprenoid compounds or derivatives. Units derived from isoprene are set off by dashed red lines. In most mammalian tissues, ubiquinone (also called coenzyme Q) has 10 isoprene units. Dolichols of animals have 17 to 21 isoprene units (85 to 105 carbon atoms), bacterial dolichols have 11, and those of plants and fungi have 14 to 24. <number>
- <number> ‘Forehead to forehead I meet thee, this third time, Moby Dick!’ [Ahab (Melville, 1851)] Head-butting during male–male aggression is a basal behavior for cetaceans Sinking of Essex (238 ton ship) in 1821 is the first documented case of a sperm whale deliberately striking a ship (Chase, 1821). http://jeb.biologists.org/cgi/content/full/205/12/1755
- <number>
- Points of unsaturation are important because they are all cis in naturally occurring fatty acids and cause a bend in the aliphatic part of the molecule. If the unsaturation was trans, the aliphatic part would look like the saturated fatty acid. <number>
- You can see that fatty acids are not very soluble in water and that the melting point increases with increasing length, but DROP DRAMATICALLY with points of unsaturation. <number>
- <number>
- To make fat, we simply add three fatty acids to glycerol as esters, see next slide. <number>
- Triacylglycerols are either fats or oils. Solid or liquid at 25oC. <number>
- Fats are stored in adipocytes as a huge mass with a bit of cytoplasm hugging it all around. <number>
- The light grey drops are triacylglycerol (oil) in the seed cells. <number>
- <number>
- <number>
- Trans fats are not natural but are made by chemists that were using vegetable oils to make margarine by hydrogenating the points of unsaturation. Trans conformation came from some of the back reactions and can make up a substantial amount of some foods. <number>
- Waxes are solid enough to be the structural component of honeycombs. <number>
- The Major types…we will do one at a time. <number>
- Glycerophospholipid structure. These are the Major membrane phospholipids. Phosphatidic acid: the arrow points to an error. What is it? Phosphatidylisonsitol-4,5-bisphosphate is correct…how it that figured. One wrong, one right about the same pKa ! Phosphatidylethanolamine and phosphatidylcholine make up most phospholipids in membranes, but all the others besides as being part of membrane structure has other roles. We will spend some time with phosphatidylinositol-4,5-bis-phosphate in Chapter 12 Biosignaling…see next slide <number>
- <number>
- <number> FIGURE 10–14 (part 1) The molecular structures of two types of membrane lipid classes are similar. Phosphatidylcholine (a glycerophospholipid) and sphingomyelin (a sphingolipid) have similar dimensions and physical properties, but presumably play different roles in membranes.
- The release of intracellular Ca2+ is from the endoplasmic reticulum, in muscles the sarcoplasmic reticulum…we will pick this up in Chapter 12. <number>
- Each phospholipase is an esterase (a hydrolase) that adds water across the ester producing one acid and one alcohol. In older texts, phospholipase A2 is phospholipase B. <number>
- What is important here is the ether links are present (formed by the condensation-dehydration of two alcohols) <number>
- <number>
- Archaea have isoprene (branched) fatty alcohols ether linked to glycerol. In the mesophilic archaea the isoprene are not covalently connected (as they are here). <number>
- Sphingosine is formed from serine and palmitic acid. Note how the fatty acid is attached to the sphingosine at the 2 position. What bond is that?? <number>
- Scraggly, but great beard. <number>
- <number>
- The polar portion at one end, non-polar is the rest. <number>
- <number>
- See that there is little difference between some of these groups glycolipids. In the membrane the sugars are on the outside with the non-polar alaphatic chains in the non polar region of the membrane. <number>
- There are diseases associated with the inability to recycle sphingolipids. Here the pathway to recycle involved converting the sphinglipid to ceramide (slide 21). Lack of a functional enzyme at any point leads to accumulation of the sphingolipid product in the nerve’s Schwan cells or deposits in these cells that cause those nerves to not work right….with a variety of nervous signs and symptoms. <number>
- Fatty acid synthesis in the cytoplasm produces palmitoyl-SCoA as the last product. The rest occurs in the endoplasmic reticulum…further elongation, 2 carbon units at a time and adding points of unsaturation at the 2 position of glycerol as a membrane lipid. Here arachidonic acid is the precursor to thee groups of local hormones: prostaglandins, leukotrienes and thromboxanes, see next slide. <number>
- First arachidonic acid is liberated from the membrane (phospholipase A2) then converted to these signaling molecules. One of the prostaglandins is responsible for the sensation of pain by it’s effect on local sensory nerves. These drugs inhibit the first enzyme in that pathway: cycloxygenase-2 and thereby inhibit or limit the sensation of pain. <number>
- We will see cholesterol and its role in membranes next chapter…but you can already see that it has only one small polar area and the rest is a relatively rigid fused aromatic with some aliphatic side chains. <number>
- Going from isoprene to cholesterol is a more than 20 step (enzyme) pathway. <number>
- This synthesis is a multi-tissue event including exposure to sun light (UV). <number>
- Vitamins are wonderful thing. Real food is full of them. <number>
- <number>
- Vitamin E is the classic antioxidant. Vitamin K is never in vitamin pills…it is made for free by our gut bacteria. Warfarin is also one of the many rat poisons…but used to prevent stroke in humans; does is important. <number>
- More isoprene lipids. <number>
- The colorful isoprenes. <number>
- <number>
- To determine the fatty acids, the TLC or column fractions are “saponified” (heated with NaOH) in the presence of methanol to form methyl esters of the fatty acids which can be easily identified by gas chromatography (classic method, see next slide). Or, each fraction can be directly analyzed by mass spectrometry. <number>
- Methyl esters of fatty acids all come of the column (gas or HPLC) at different times. The columns are calibrated with standards. <number>
- The lipid unfragmented has an m/z of 371. Please see there are m/z’s that do not correspond to the molecular diagram, these are fragments when a molecule is fragmented in two places simultaneously and do not aid in the determination of the structure (Example m/z = 151). Note also that some fragments are present in greater abundance because those single bonds are more liable than others. <number>
- Some of these groups were not stressed because they are in pathways leading to other lipids: example on the prenol lipids (branched chains) farnesol and geraniol are intermediateds to sterol lipids and other lipid classes (carotenoids, isoprene vitamins, etc.). <number>