BS Nursing Level 1: Biochemistry Lipids PDF

BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh LIPIDS Lipids are hydrophobic, nonpolar molecules. They are soluble in nonpolar solvent. They are insoluble in polar solvents, such as water. They are isolated from the other biological molecules by...

BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh LIPIDS Lipids are hydrophobic, nonpolar molecules. They are soluble in nonpolar solvent. They are insoluble in polar solvents, such as water. They are isolated from the other biological molecules by extracting them with nonpolar Fatty acids typically contain between 12 and 20 solvents. carbons The number is usually always even. Two methods of sub classifying lipids is The nonpolar tails interact with London based upon; forces. In terms of carbon chain length, characterized Biochemical function by three (3) 1. Energy-storage lipids Long-chain fatty acid - C12 - C26 (triacylglycerols) Medium-chain fatty acid - C8 - C10 2. Membrane lipids Short-chain fatty acid - C4 - C26 (phospholipids, sphingoglycolipids, and Types of Fatty acids cholesterol 3. Emulsification lipids (bile A. SATURATED & UNSATURATED, some acids) fatty acids contain double bonds or not: 4. Messenger lipids (steroid hormones and eicosanoids) Saturated FA 5. Protective-coating lipids (biological waxes) Whether or not saponification occurs when placed in basic solutions Monounsaturated 1. Saponifiable lipids FA (triacylglycerols, phospholipids, sphingoglycolipids, and biological waxes) 2. Nonsaponifiable lipids Polyunsaturated FA (cholesterol, steroid hormones, bile acids and eicosanoids) Fatty Acids ○ In the carboxylic acid family B. Unsaturated FA and Double bond Waxes position ○ Fatty Acids + Alcohols Shorthand position system for specifying Triglycerides key structural parameters for FA ○ 3 Fatty acids + glycerol Two number separated by a colon to Phospholipids and glycolipids specify no. of carbons and no. of ○ 2 fatty acids + glycerol + carbon-carbon double bonds phosphate + X ○ Ex. 18:0 = 18 carbon and no Steroids double bond ○ Derivatives of cholesterol Preceding notation: delta sign and Eicosanoids one/more superscript ○ Derivatives of the Fatty acid ○ Ex. △ 9, 12, 15 = 3 double bonds arachidonic acid at location 9, 12 and 15 Membranes Different families of unsaturated fatty ○ Formed from phospholipids and acid exist specifying double bond glycolipids position relative No methyl group" Double bond is denoted using Greek FATTY ACIDS lower case omega (ω) Fatty acids contain a carboxylic acid group ○ Ex. Omega-3 fatty acid = This should make them quite polar unsaturated fatty acid with its However, they also contain a long hydrocarbon endmost double bond three tail carbons away from its methyl end Which overall, makes them nonpolar. Powaei || 1 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh ○ Ex. Omega-6 fatty acid = unsaturated fatty acid with its PROPERTIES OF FATTY ACIDS endmost double bond six carbons 1. Melting points influenced by carbon away from its methyl end chain length and degree of unsaturation (no. of double bonds present) Degree of unsaturation: Normally the double bonds are cis This lowers the melting points for fatty acids containing double bonds. Linolenic acid is one of the omega - 3 fatty acids BIOLOGICALLY IMPORTANT FATTY ACIDS The cis double bonds produce kinks, which disrupt the London forces by preventing the tails from packing close to one another. 2. Water solubility influenced by carbon chain length Solubility indirectly proportional to the no. of carbon Short-chain = slightly soluble in water Long-chain = insoluble in water As acids, the carboxylic acid group in fatty acids can react with a base to produce a carboxylate ion Powaei || 2 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh By donating its proton (H+) to the base the fatty acid becomes negatively charged. Triglycerides are a combination of three 3 fatty acid molecules with a glycerol molecule (an alcohol molecule). The negative charge makes the polar head portion of the fatty acid even more polar and hydrophilic. The salts of fatty acids are also called soaps, and are considered amphipathic, meaning they have a part that is very hydrophobic along with a part that is very hydrophilic. Glycerol, which is also called glycerin, is amphipathic molecules form an alcohol with three hydroxyl groups. interesting structures when exposed to water. As with the waxes, the fatty acids can react with ALCOHOL, CARBOXYLIC ACIDS & ESTERS the hydroxyl groups to We look now at three families that are form esters. distinguished by a functional group that Since there are three contains the element oxygen. hydroxyl groups, three Esters fatty acids can react to Chemically, esters can be synthesized by form three esters. reacting a carboxylic acid with and alcohol: Ethyl Propanoate For triglycerides, all three hydroxyls of the glycerol have a fatty acid residue REACTIONS INVOLVING WATER attached to it. Hydrolysis Hydrolysis can also be catalyzed using a base (OH-): ○ Because one of the products of the hydrolysis is a carboxylic acid, in base catalyzed hydrolysis the base undergoes a second acid/base reaction with the carboxylic acid to produce a carboxylate ion. ○ The base catalyzed hydrolysis of esters is also called saponification TRIACYLGLYCEROLS Figure 8.6 Energy - Storage Lipids from Triglycerides are a storage form of fatty acids Raymond in mammals. Often when blood tests are done, they measure your triglyceride levels. High triglyceride levels in the blood are a risk indicator for atherosclerosis. Powaei || 3 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Triacylglycerol/triacylglycerides is a lipid Dietary fats and oils formed by esterification of three fatty acids to a glycerol molecule Simple triacylglycerols – triester formed from the esterification of glycerol with three identical fatty acid molecules Mixed triacylglycerols - triester formed from the esterification of glycerol with more than one kind of fatty acid molecule This is why when you eat more than you need to meet your energy requirements, the excess energy is stored in the form of fat. Fat can store almost twice as much energy per gram as carbohydrates and proteins In mammals the fats are stored in the adipose tissue. Just as with fatty acids, where the presence of Adipose tissue also functions to protect cis double bonds lower the melting points, organs from shock and cold. triglycerides made from unsaturated fatty acids have lower melting points than those made DIETARY CONSIDERATIONS & from saturated fatty acids. TRIACYLGLYCEROLS Triglycerides from animals tend to have “Good fat vs Bad fats” a higher proportion of saturated fatty ○ Type of dietary fat and amount acids. determines the response to it. ○ Most are solids at room ○ Recommended daily intake – temperature (25⁰) and are called 30% total calories (15MUFA’s, fats. 10PUFA and 10SFA) ○ Examples include: butter, lard ○ SFA = bad (heart), MUFA = good, and bacon grease PUFA = good/bad (heart/cancer) Triglycerides from plants tend to have a Omega-3 and omega-6 higher proportion of unsaturated fatty ○ Inuit diet – high in omega-3 acids. (from fish); American – high in ○ Most are liquids at room omega-6 (from plant oils) temperature and are called oils. ○ Intake several servings of fish ○ Examples include: corn oil, canola each week, the choice of fish is oil, peanut oil and olive oil. important (deep-cold water including herring, tuna and Triglycerides from animals tend to have salmon) a higher melting points ○ Fats = linear ; Oils = bends in their chains Pure fats and oils are colorless, odorless and tasteless. Powaei || 4 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Essential Fatty acid - is a fatty acid CHEMICAL REACTIONS OF needed in the human body that must be TRIACYLGLYCEROLS obtained from dietary sources because it Reactions that involve triglycerides include: cannot be synthesized within the body, 1. Hydrolysis in adequate amounts. 2. Hydrogenation 3. Oxidation 4. Base-catalyzedNNhydrolysis (saponification) 1. Hydrolysis ○ Acidic conditions – glycerol and fatty acids ○ Basic conditions – glycerol and fatty acid salts ○ Stomach hydrolysis forms into Essential Fatty acid diacylglycerols (one of the outer Linoleic acid → (18:2) fatty acid is removed), then arachidonic acid (20:4) another outer core is removed ○ arachidonic acid (20:4) – major forming monoacylglycerols starting material for eicosanoids Partial hydrolysis - 1/more fatty acid (substances that help regulate remains attached to the glycerol blood pressure, clotting and other Complete hydrolysis - all free fatty important functions) acids are removed Linolenic acid (18:3) → Saponification of triglycerides EPA (20:5) → DHA (22:6) Saponification is the base-catalyzed ○ EPA (eicosapentaenoic acid) and hydrolysis of the ester bonds in a DHA (docosahexaenoic acid) – triglyceride. important constituents of the Products: glycerol and fatty acid salts communication membranes of ○ 1st step: fat or oil + 3H2O the brain and are necessary for → 3 fatty acids + glycerols normal brain development ○ 2nd step: 3 fatty acid + 3NaOH Missing from diet results to: ○ Red and irritated skins, infections → 3 fatty acids salts + 3H2O and dehydrations are likely to occur and liver abnormalities Saponification of animal fat – soap-making Fat substitutes Soapmaking – heating lard (fat) with lye ○ Substances that create the (ashes of wood, impure form of KOH) sensations of creaminess and richness of taste without the 2. Hydrogenation negative effects associated with Involves hydrogen addition across dietary (heart disease and carbon-carbon multiple bonds, which obesity) increases degree of saturation as some multiple bonds are converted to single bonds ○ Unsaturated fats and oils contain alkenes and can be hydrogenated to produce saturated fats. ○ Commercially, vegetable oils are often hydrogenated to produce a solid product that has better qualities for making baked goods. Animal fats, such as butter and lard, which are naturally saturated, can also be used, but unlike the vegetable oils, they come with cholesterol, Powaei || 5 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh which is undesirable for health reasons. Phospholipids are the most abundant type of membrane lipid. It is a lipid that Another type of oxidation/reduction contains one or more fatty acids, a reaction is the hydrogenation reaction: phosphate group, a platform molecule to ○ In this example, an alkene is which the fatty acids and phosphate are reduced to an alkane. attached, and an alcohol that is attached This is considered to the phosphate group. reduction, because the hydrogen is bringing in additional electrons to the molecule. ○ The alkane that is produced in this reaction is considered “saturated” because it can no longer absorb any more hydrogen atoms. Hydrogenation of triglycerides Partial hydrogenation cab produces trans fats. There are two types of phospholipids ○ Trans fats have been found to ○ Glycerophospholipids lower your HDL (“Good ○ Sphingolipids cholesterol”) levels. Glycerophospholipids The Glycerophospholipids have a 3. Oxidation of triglycerides structure similar to triglycerides, with Unsaturated triglycerides can react with one of the fatty acids replaced with a oxygen to produce small chain fatty phosphate. acids and other small molecules. ○ These often do not smell very good ○ This is what happens when butter goes rancid. ○ This makes solid fats and oils more stable than liquid oils and is why the solid fats are preferred The Glycerophospholipids is a lipid that for deep frying. contains 2 fatty acids and a phosphate ○ Antioxidants group esterified to a glycerol molecule ○ Vitamin C and Vitamin E (natural) and an alcohol esteried to the phosphate BHT and BHA group The Glycerophospholipids have a Membrane Lipids: structure similar to triglycerides, with Phospholipids one of the fatty acids replaced with a phosphate. “Phosphatidyl-” refers to everything but the X Phospholipids and Glycolipids are the stuff that biological membranes are made of. - Phosphatidylcholines are used - Like the soaps, these molecules are commercially as emulsifying agents. highly amphipathic, and when mixed ○ An emulsifying agent stabilizes with water spontaneously form an emulsion. membranes that are described as lipid bilayers. Powaei || 6 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh ○ An emulsion is a colloidal suspension of one liquid in Phospholipids and Glycolipids another. Phospholipids An example is The sphingolipids function similarly to mayonnaise, which is a the glycerophospholipids, but colloidal suspension of oil structurally they are different. and water. ○ There is not glycerol core Lecithin, which is another name for ○ The glycerol and one of the fatty phosphatidylcholine, is used as an acids found in emulsifying agent in mayonnaise, ice glycerophospholipids is replaced cream and mustard. with a molecule called Cephalins, another name for sphingosine. phosphatidylethanolamines and phosphatidyl serines; found in heart, liver and brain tissue. Glycerophospholipids Triacylglycerols Component of cell Storage molecules membrane polar nonpolar Sphingolipids Sphingolipids are made up of sphingosine, a fatty acid, a phosphate group and an alcohol Membrane Lipids: Cholesterol Cholesterol is a Steroids ○ Steroids are a type of lipid that is not derived from a fatty acid. They are based instead on a system of four cycloalkane rings that are fused together (3 six-membered rings and 1 five-membered ring). Sphingomyelin – an important structural component of myelin sheath,the protective and insulating coating of the nerve cells Membrane Lipids: Glycolipids/Sphingoglycolipids A lipid that contains both a fatty acid and a carbohydrate component attached to a sphingosine molecule. Sphingoglycolipids and sphingophospholipids Characteristics: Have similar head and tail, only that No polar head, =O or OH at carbon 3 – they differ in constituents ( mono- or “head” oligosaccharides vs phosphate alcohol) Found in different part of the body: cell Cerebrosides simplest membrane (25%), nerve tissue and sphingoglycolipids brain (10%), all fluids (100mL = 50mg While gangliosides is a more complex free & 170mg cholesterol with various which contains branched chain up to 7 fatty acids) monosaccharide residues A portion of cholesterol is obtained from dietary intake (liver, intestine) Distributed to cells through the body for various uses via the bloodstream, lipoprotein (protein carrier) Powaei || 7 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Atherosclerosis – more LDL low HDL; buildup of plaque along the inner walls of arteries Steroids Cholesterol is only found in animals Besides being used to synthesize the other steroids, cholesterol is dissolved in membranes to keep them fluid. ○ Plants use the alternative strategy of using polyunsaturated fatty acids to make their phospholipids. Most lipid molecules in the bilayer Lipoproteins contain at least one unsaturated fatty Lipoproteins are used to transport the acid. Presence of kinks presence of kinks water insoluble lipids such as prevent tight packing of the fatty acid triglycerides, phospholipids and chains cholesterol, in the blood. Open packing imparts a flexible or fluid Lipoproteins contain lipids and proteins. character to the membrane – a necessity They include: because numerous types of biochemicals ○ Chylomicrons transport must pass into and out of a cell. primarily triglycerides from the Cholesterol are also components of cell digestive tract. membrane – regulating rigidity. ○ LDLs (low density lipoproteins) Within the membrane, cholesterol transport cholesterol, molecules orientation is “head” triglycerides and phospholipids (hydroxyl group) to the exterior lipid from the liver to other tissues. bilayer and “tail” (steroid ring system ○ HDLs (high density lipoproteins) with alkyl group) to the interior lipid transport cholesterol and bilayer phospholipids back to the liver. Proteins are also components of lipid bilayer: The HDL and LDL levels in the blood can be Carbohydrates, usually oligosaccharides used to assess one's risk for atherosclerosis. are also components of the cell High levels of HDL is considered good membranes. ○ This is why HDL is sometimes Carbohydrate-protein complex is called referred to as “good cholesterol” glycoproteins while carbohydrate-lipid ○ > 40 mg/dL is good. complex is called glycolipids are High levels of LDL is considered bad markers. ○ This is why LDL is sometimes Markers, substances that play a key role referred to as “bad cholesterol” in the process by which different cells ○ > 100 mg/dL is bad. recognize each other Ex. Blood types Cell Membrane Intermolecular forces rather than Living cells contain an estimated 10,000 covalent governs the interactions among different kinds of molecules in an the lipid and protein components of the aqueous environment confined by a cell lipid bilayer which does require them to membrane. move freely like dancers in a crowded A cell membrane lipid-based aqueous floor. structure that separates a cell’s TRANSPORT ACROSS CELL aqueous-based interior from the MEMBRANES aqueous environment surrounding the ○ Passive transport cell. Transport process in which a substance moves across a cell membrane by diffusion from a region of higher concentration to a region of lower concentration without the expenditure of any cellular energy. ○ Facilitated transport – “carriers or transporter” Powaei || 8 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Transport process in which a substance moves across Messenger Lipids: a cell membrane, with the Steroid Hormones aid of membrane proteins, from a region of higher Hormone concentration to a - A biochemical substance region of lower produced by ductless glands that concentration without has a messenger function. the expenditure of cellular Steroid Hormones energy. - Cholesterol derivative hormone Active transport – “pumps” Two types: - Transport process in which Sex hormones - controls reproduction a substance moves across and secondary sex characteristics a cell membrane, with the CLASSIFIED INTO THREE (3) aid of membrane proteins, SUBCLASSES against a concentration ○ Estrogens – female sex gradient with the hormones. expenditure of cellular ○ Androgens – male sex hormones. energy. ○ Progestins – pregnancy hormones Adrenocorticoid hormones - controls Emulsification Lipids: reproduction and secondary sex Bile acids characteristics (produced by adrenal Emulsifier glands) - Is a substance that can disperse and CLASSIFIED INTO TWO (2) SUBCLASSES stabilize water-insoluble substances as ○ Mineralocorticoids – controls the colloidal particles in an aqueous solution. balance between Na+ and K+ Bile acid ions in cells and body fluids - A cholesterol derivative that functions as ○ Glucocorticoids – control glucose a lipid-emulsifying agent in the aqueous metabolism and counteract environment inflammation. Two types: Simple (free) bile acids - Steroid Steroid Hormones: Sex hormones monocarboxylic acids; Obtained by Estrogens oxidation of cholesterol that differ in two - Synthesized in the ovaries and adrenal aspects: cortex (outer part of adrenal glands on ○ They are tri-or dihydroxy top of each kidney) cholesterol derivatives FUNCTIONS: ○ The carbon 17 side chain of Development of female secondary sex cholesterol has been oxidized to a characteristics at the onset of puberty carboxylic acid. Regulation of menstrual cycle Complexed bile acids - conversion of Development of mammary gland during more complex by attachment of amino pregnancy and induce estrus (heat in acid to carbon 17 animals) Androgens Enhanced emulsifying ability stemming from - Synthesized in the testes and adrenal one end of molecules being hydrophilic and the cortex (outer part of adrenal glands on rest of the molecule being hydrophobic. top of each kidney) FUNCTIONS: Bile Development of male secondary sex - The medium to which the bile is supplied characteristics and muscle growth through the small intestines Progestins - Is a fluid containing emulsifying agents - Synthesized in the ovaries and placenta that is secreted by the liver, stored in (outer part of adrenal glands on top of the gallbladder and release into the each kidney) small intestines during digestion FUNCTIONS: prepare lining of uterus for the Imbalance between cholesterol and bile pool in implantation of fertilized ovum & – increase secretion of cholesterol and decrease suppress ovulation in bile results in gallbladder stone. Powaei || 9 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Steroid Hormones: Sex hormones anti-inflammatory effects Natural & Synthetic steroids in the body Cortisone and prednisolone used for inflammatory disease like RA Synthetic steroids Two types: ○ Oral Contraceptives Messenger Lipids: Suppress ovulation as a Eicosanoids method of birth control Eicosanoids A mixture of synthetic - An oxygenated C20-fatty acid derivative estrogen (regulates that function as a messenger lipid menstrual cycle) and - Greek word “eikos” meaning 20, with synthetic progestin arachidonic acid as precursor (20:4) (prevents ovulation) is fatty acid. used creating false sense - Hormone-like substances = not of pregnancy transported into bloodstream but exert “morning after” pill = aka in tissues where they are synthesized “RU-486” developed in Physiological effects mediated: France interferes with the Inflammatory response gestation of a fertilized Production of pain and fever egg and terminates a Regulation of blood pressure pregnancy within the first Induction of blood clotting nine weeks of gestation Control of reproductive functions more effectively and safely (induction of labor) than surgical methods Regulation of sleep/wake cycle Three types of eicosanoids: ○ Anabolic steroids ○ Prostaglandins Used illegally by some ○ Thromboxanes athletes to increase ○ Leukotrienes endurance and strength methandrostenolone Prostaglandins similar structure with - A messenger lipid that is a C20-fatty testosterone acid derivative containing cyclopentane Steroid Hormones: ring and oxygen-containing functional Adrenocorticoid hormones group Functions: Two types: Raising body temperature ○ Mineralocorticoids Inhibition of secretion of gastric juices ALDOSTERONE (major Increasing secretion of a protective hormone) mucus layer into the stomach ○ Glucocorticoids Relaxing and contracting smooth muscle CORTISOL/HYDROCORTIS Directing water and electrolyte balance ONE (major hormone) Intensifying pain and enhancing largest synthesized inflammation responses hormone by the adrenal Thromboxane, A2 glands - An oxygenated C20-fatty acid derivative Together with cortisone that contains a cyclic ether ring and (synthetic form) powerful oxygen-containing functional group Powaei || 10 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Functions: promotion of blood clots Leukotriene, A4 - A messenger lipid that is a C20-fatty Chemical action classification: acid derivative containing three 1. Saponifiable conjugated double bonds and hydroxyl - Lipid that undergoes hydrolysis in basic groups solution to yield two or more smaller - Present in leukocytes (WBC) = elevation product molecules – allergy and inflammatory Types of Linkages in Saponifiable lipids: Protective-Coating Lipids: Biological waxes Waxes are made by combining fatty acids with long chain alcohols. It was discussed how carboxylic acids react with alcohols to form esters. Waxes are esters. When two more molecules combine to form a larger molecule, the word residue is used to indicate which molecule that part of the larger molecule came from. Waxes are very hydrophobic and are used by plants and animals for protective, water-proof coatings 2. Nonsaponifiable - Does not undergoes hydrolysis in basic solution - Common: one building block present --- four-ring steroid nucleus no need for linkages since you have one platform Lanolin – a mixture of waxes obtained only from sheep wool; a base for cream and ointment intended to enhance water REFERENCES retention “MA’AM PPT” Powaei || 11 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh APPENDIX Powaei || 12 BS NURSING LEVEL 1: BIOCHEMISTRY LIPIDS Angelica C. Lopez, RPh Powaei || 13