Week 4 - Carbohydrate Chemistry

Carbohydrate Chemistry When you hear carbohydrates what comes into your minds Objectives To define carbohydrates in chemical terms To classify carbohydrates into major groups with examples for each group To describe important properties of carbohydrates To describe the biomedical importa...

Carbohydrate Chemistry When you hear carbohydrates what comes into your minds Objectives To define carbohydrates in chemical terms To classify carbohydrates into major groups with examples for each group To describe important properties of carbohydrates To describe the biomedical importance of carbohydrates To learn the overview of carbohydrate metabolism What is Carbohydrates “Hydrate of Carbon” Chemically simple – contains three elements (C·H2O)n Carbohydrates are the most abundant molecule in nature Chemically defined as polyhydroxy aldehydes and ketones or substances that hydrolyzes to yield polyhydroxy aldehyde and ketone. The term 'sugar' is frequently applied to monosaccharides and lower oligosaccharides. IUPAC-IUBMB Joint Commission on Biochemical Nomenclature (JCBN) Importance of carbohydrates Is the most abundant class of bioorganic molecules on planet earth Aside from dietary food , that we eat carbs can be also in the form of cotton or linen that can be used for clothing Ideally, the average human diet should be composed of 2/3 carbohydrates What are some of the function of carbohydrates Storage form of Structural Source of energy Dietary fiber energy component Cellular Constituent of Intercommunicat Detoxification nucleotides ion, Lubrication, and Immunity General Properties Asymmetric carbon: a carbon to which four different atoms or groups of atoms are attached Stereoisomers: compounds which are identical in composition and differs only in spatial configuration Optical activity: when a beam of plane-polarized light is passed through a solution exhibiting optical activity, it will be rotated to the right or left Dextrorotatory (d or + sign) Levorotatory (l or –sign) racemic Aldehyde sugars (polyhydroxy aldehyde) Ketose sugar (Polyhydroxy ketone) Classify each of the ff: monosaccharides according to both the number of carbon atoms and the type of carbonyl group Structural Representations of Sugar Fisher projection: straight chain representation Haworth projection: simple ring in perspective Conformational representation: chair and boat configurations Structural Representations of Sugar Representation Structure Advantages Disadvantages Doesn't accurately Simple to draw and represent cyclic Fisher projection Straight chain understand chirality structure Accurate Can be difficult to representation of cyclic visualize 3D Haworth projection Cyclic structure structure conformation Accurate representation of 3D conformation And understand affect the stability and Conformational 3D arrangement of reactivity of the sugar Can be complex and representation atoms molecule. difficult to draw Structural representation Sugars can be drawn in the straight chain form as either Fisher projections or perspective structural formulas. ENANTIOMERS D L Glyceraldehyde Typically but not always These molecules have a measurable D - sugars optical rotation, which depends upon L – amino acids both the monomer residues and their conformation  Haworth projections are more realistic than the Fisher projections In general, if a substituents points to the right in the Fisher structure, it points down in the Haworth. if it points left, it points up. α and β anomers: OH group on the same side of the oxygen ring: α anomer OH group on the opposite side of the oxygen ring: β anomer CHIRALITY Chiral center – an atom in a molecule that has 4 different group tetrahedrally bonded to it Chiral molecule – a molecule whose mirror image are non superimposable Achiral molecule – a molecule whose mirror image are superimposable Classification and Nomenclature Monosaccharide names classify the compounds in two ways simultaneously, by combining two kinds of prefixes before –ose: Those with an aldehyde group are aldoses; those with a ketone group are ketoses Those with three, four, five and six carbons are trioses, tetroses, pentoses and hexoses respectively D- Glucose ( Aldohexose) Grape sugar , Dextrose , Blood sugar Most abundant in nature Most important from a human nutritional standpoint Tastes sweet and nutritious. They are usually ripe fruits – ripe grapes that has 20-30% glucose by mass Cell use glucose as a primary source of energy D- glucose = sweet and nutritious L – glucose = tasteless , the body cannot use it USE OF MONOSACCHARIDE Glucose ( 50%) is hypertonic and provides a source of calories in a minimal volume of water. Glucose 50% is frequently used to restore blood glucose concentrations in the treatment of hypoglycemia resulting from insulin excess or from other causes. Galactose (aldohexose) Brain Sugar ( it is a component of glycoproteins found in the brain and nerve tissue Synthesized from glucose in the mammary glands for use in lactose What makes it important: A component of glycoproteins found in brain and nerve tissue Present in the chemical markers that distinguish various types of blood D- Fructose ( Ketohexose) Levulose, Fruit Sugar Most important ketohexose Found in many fruits Main sugar in semen The most sweetest tasting of all sugars, found in many fruits and it is equal in honey in equal amounts with glucose Used as a dietary sugar not because it has a fewer in calories per gram but because less is needed for the same amount of sweetness Structurally identical to glucose from carbon 3 to 6 Uses of Monosaccharides Fructose: as an intravenous energy source for patients with: Hepatic disease, Uncontrolled diabetes mellitus Postoperative state. What is Disaccharides? A disaccharide consists of 2 monosaccharide units held together by a glycosidic bond( links a sugar to another group) Disaccharides Sucrose Lactose Maltose Condensation products of two monosaccharide units Homo oligosaccharide Maltose (D-glucopyranosyl- α-1,4-D-glucopyranose) Isomaltose (D-glucopyranosyl- α-1,6-Dglucopyranose) Cellobiose (D-glucopyranosyl- β-1,4-Dglucopyranose) Hetero oligosaccharide Lactose (D-galactopyranosyl-β-1,4-D-glucopyranose) Sucrose (D-glucopyranosyl-α-1,2-D-fructofuranoside) Glycosidic linkage The bond that links the two monosaccharides of a disaccharide together The bond in the disaccharide resulting to form the reaction between the hemiacetal carbon atom OH group of one monosaccharide and other OH group of monosaccharide It is always carbon – oxygen – carbon bond in a disaccharide MEME TIME MONOSACCHARIDE MONOSACCHARIDE Cellobiose Produced as an intermediate in the hydrolysis of the polysaccharide cellulose Contains two D-glucose monosaccharide units linked through 91-4 glycosidic linkage. It differs in maltose in one of the D-glucose untis , it has a beta configuration Cannot be digested by humans  Sucrose Common table sugar, cane sugar Most abundant disaccharide Found in fruits and vegetables Sucrose is a nonreducing sugar. No hemiacetal is present in the molecule because of the glycosidic linkages involve by the reducing Formed by the acetal formation between the hemiacetal –OH of agent α-D-glucose and β-D-fructose In the solid state and in solution Linkage: α,β (1 2) exist in only one for there are no beta or alpha isomers The open chain form is not possible for this Lactose Milk sugar Occurs naturally only in milk Enzymes in mammalian mammary glands take glucose from the blood stream and synthesizing lactose Milk contains the α and β anomers of lactose in a 2:3 ratio b-lactose is sweeter and more Souring of milk is caused by the soluble than ordinary a- lactose conversion of lactose to lactic Contains D-galactose and D-glucose acid by bacteria in the milk joined by a β(1 - 4) glycosidic linkage From the hemiacetal –OH (at C1) of D-galactose to the C4 position of D-glucose Why does milk bother me? At your best friend's blowout party (for you! - having been accepted to medical school) last weekend, everyone pigged out on cheese burger, cheese pizza, ice cream and fruit shake. You were having a great time, but after about an hour you started feeling awful. First your stomach felt really full - almost too full. Then it started to ache and you had a lot of gas - phew! Before long, you were running to the bathroom because you had to poop and you couldn't wait! Oh, no! Maltose Malt sugar or corn sugar Produced by the partial hydrolysis of starch by amylase Produced whenever the polysaccharide starch breaks down, as happens in plants when seeds germinate and in human beings during starches digestion Common ingredients in baby food and found in malted milk Malt – geminated barley that has been baked or ground. It Formed by two D-glucose residues contains maltose linked by an α(1 4) glycosidic linkage Uses of Disaccharides Maltose can be converted from icodextrin which is used in dialysis solutions. Sucrose : It is often used in medications to impart a more pleasant taste to often unpalatable chemicals Iron Sucrose : is a medicine which is used in iron deficiency POLYSACCHARIDES: Made up of repeating units of monosaccharides held by glycosidic bonds During its formation, a water molecule is released at each condensation 4 parameters to distinguish POLYSACCHARIDES Identify of the monosaccharide repeating unit in the polymer chain which is homopolysac or heteropolysac Length of the polymer chain Type of glycosidic linkage between monomer units A &B The degree of the branching of the polymer chain POLYSACCHARIDES: They are ideal as STORAGE AND AS STRUCTURAL COMPONENTS They are of 2 types Homoglycans and Heteroglycans. Polysaccharides Homoglycans Amylose: linear chain of α-D-glucose linked via α-1,4 glycosidic bonds Amylopectin: branched chain structure composed of α-D- glucose in α-1,4 linkages and α-1,6 linkages at branching points Starch: a mixture of amylose and amylopectin Glycogen: resembles amylopectin in having α-1,6 branches from an α-1,4 chain, although more branched Cellulose: unbranched chain of D-glucose with β-1,4 linkages Starch ❑Polymers of D-glucose ❑α-linkage in starch, β-linkage in cellulose Types of starches distinguished by degree of chain branching: Amylose- linear polymer of glucose linked by α(1,4) bonds Amylopectin- branched-chain polymer with branches starting at α(1,6) linkages along the chain of α(1,4) linkages Amylose and amylopectin are the 2 forms of starch. Amylopectin is a highly branched structure, with branches occurring every 12 to 30 residues USES OF POLYSACCHARIDES This polysaccharide is produced by most green plants as an energy store Starch Unlike cellulose, starch can be metabolized by humans. Starches provide the bulk of the energy we obtain from grains, potatoes etc. Amylose Amylopectin Suspensions of amylose in water adopt a helical conformation Iodine (I2) can insert in the middle of the amylose helix to give a blue color that is characteristic and diagnostic for starch Cellulose Linear homopolymer of b-D-glucose all linked by b(1,4) glycosidic bonds Most abundant of all carbohydrates Individual polysaccharide chains are hydrogen bonded giving plant fibers mechanical strength Cellulose n ~ 5000-10000 Also found in some bacteria, Wood cell (fiber) cell walls algae, fungi, seed hairs, and are made of cellulose + animals (tunicates or sea Microfibrils lignin and hemicelluloses squirts) of cellulose  Cellulases are found in bacteria including those that inhabit the digestive tracts of grazing animals and insects Yields glucose upon complete hydrolysis Partial hydrolysis yields cellobiose Gives no color with iodine  Why can’t we eat cellulose? An angry delusional vegan is making you eat grass Why grass is a good food for a cow and not for humans? They learned from their teacher that potatoes, rice and cellulose in grass have Animals lack the enzyme similarities in their cellulase which composition butattack β- not grass linkages Glycogen A highly branched polymer of glucose.. Glycogen Known as animal starch Branched-chain polymer of α-D- glucose with a chain of α(1,4) linkages with α(1,6) linkages at branch points Branch points occur every 10 residues (every 25 in amylopectin) Stored in muscle and liver Glycogen and iodine gives a red- violet color USES OF POLYSACCHARIDES Glycogen: Storage of excess sugar in animals; Stored in liver and muscles It is the animal short-term storage form of energy Chitin Similar in structure and function as cellulose Linear homopolysaccharide with all residues linked in β(1,4) glycosidic bonds Monomer is N-acetyl-β-D-glucosamine Major structural component of the exoskeletons of insects and crustaceans and in cell walls of algae, fungi, and yeasts USES OF POLYSACCHARIDES CHITIN: USED AS A STRUCTURAL MATERIAL IN Dextrins produced by the partial hydrolysis of starch amylodextrins, erythrodextrins or achrodextrins used in infant formulas to prevent the curdling of milk in baby’s stomach Dextrans contains α (1,4), α (1,6) and α (1,3) linkages MW: 40,000; 70,000; 75,000 used as plasma also used as extenders in molecular the sieves in gel treatment of filtration shock chromatograph y USES OF POLYSACCHARIDES Dextran : Polysaccharide made of many glucose It is used medicinally as an antithrombotic, to reduce blood viscosity Glycosoaminoglycans Complex carbohydrates containing amino sugars and uronic acids May be attached to a protein molecule to form a proteoglycan Proteoglycans provide the ground or packing substance of connective tissue Glycosoaminoglycans (mucopolysaccharides) Long unbranched polysaccharide chains composed of repeating disaccharide units – a uronic acid (except keratan sulfate) and an amino sugar. The different classes are distinguished by: Sugar residue Type of linkage between these residues Number and location of the sulfate groups Repeating disaccharide unit:D- Repeating disaccharide unit: glucoronic acid or L-iduronic acid D-galactose and N-acetyl-D glucosamine-6-sulfate Linkage of the two sugars is by Linkage of the two sugars is by β- β-1,3 and in between 1,4 and in between disaccharide disaccharide units is β-1,4 units is β-1,3 Carbohydrates as membrane components Bacterial cell wall Bacterial cell wall is made of carbohydrates covering the outside of cell membrane. Gram positive bacteria have simpler but a thick wall of peptidoglycan Gram negative have less peptidoglycan, but more complex in structure with periplasmic space and lipopolysaccharides. Plant cells also use cell wall to stabilize their structures. Animal cells have extra-cellular (outside of the cell) matrix instead and they are more dynamics (being formed or disorganized quickly). Bacterial cell wall Bacterial cell wall polysaccharides consist of repeating units of N-acetyl glucosamine and N- acetylmuramic acid linked by β-1,4 bonds. USES OF POLYSACCHARIDES Inulin Polymer of fructose i.e. fructosan Found in bulbs, garlic, onion etc. Inulin is not readily metabolized in the human body and is readily filtered through the kidney. Hence used for testing kidney function  Biomedical Importance of Carbohydrates Preferential source of energy Form of stored chemical energy Cellular structure (chitin, cellulose, pectins) Components of biologically important substances Aid in molecular recognition EXCESS CARBOHYDRATES What is Glucose oxidase? Glucose oxidase converts glucose to gluconic acid and hydrogen peroxide When the reaction is performed in the presence of peroxidase and o-dianisidine a yellow color is formed The basis for the measurement of urinary and blood glucose Testape, Clinistix, Diastix (urinary glucose) Dextrostix (venous glucose) Glucose measurement methods Most These methods are reactions enzymatic produce either methods a product that 3 enzyme can be systems are measured currently used photometricall to measure y or an glucose: electrical Glucose oxidase current that is Glucose proportional dehydrogenase to the initial Hexokinase glucose concentration Esterification Reactions The hydorxyl group of sugars can react with acids and derivatives of acids to form esters. Phosphate esters are the usual intermediates in the breakdown of carbohydrates to provide energy. Oxidation to produce acidic sugars The primary alcohol oxidize into aldehyde and the aldehyde is then will undergo oxidation to produce carboxylic acid. Reduction to produce sugar alcohol Aldehyde will be reduced to primary alcohol The main product/end product is the sugar alcohol called Alditol Reduction Sorbitol Used as moisturizing agent in food and cosmetics industry High affinity for water Also used as a sweeting agent in chewing Glucose after reduction will become sorbitol Carbohydrate Metabolism Terms to Remember  Glycolysis Glycolysis is the process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytoplasm of a cell and does not require oxygen. Glyconeogenesis is the process of creating glycogen and sugars like glucose from non- carbohydrate sources, such as amino acids and lactate. Importance of Gluconeogenesis During deprivation, the gluconeogenesis cycle is important for blood glucose regulation. Many cells and tissues, including RBCs, neurons, skeletal muscle, the medulla of the kidney, testes, and embryonic tissue, rely on glucose to meet their energy needs. The Neoglucogenesis cycle removes metabolites such as lactate (produced by muscles and RBCs) and glycerol from the bloodstream (produced from adipose tissue). Gluconeogenesis takes place in the liver and cortex of kidneys. It usually takes place when the carbohydrates in the diet are insufficient to meet the demand of glucose in the body. Glucagon is a hormone that is secreted by the α-cells of pancreatic islets when the body’s blood glucose level begins to drop. By two mechanisms, glucagon regulates the transition of fructose 1, 6-bisphosphate to fructose 6-phosphate or promotes the process of gluconeogenesis. What is Glycogenesis Glycogenesis is the metabolic process by which glucose is converted into glycogen and stored primarily in the liver and muscles. It is essential for maintaining blood sugar levels and providing a readily available energy source. Glycogen Storage Liver glycogen: Serves as a glucose reservoir for the whole body, especially during fasting. Muscle glycogen: Primarily used as a local energy source for muscle contraction. Regulation of Glycogenesis: Insulin: Stimulates glycogenesis by activating glycogen synthase and inhibiting glycogenolysis (the breakdown of glycogen). Glucagon: Stimulates glycogenolysis and inhibits glycogenesis. Adrenaline: Stimulates glycogenolysis in muscle cells to provide energy for a fight-or-flight response. Allosteric regulation: Glucose-6-phosphate can allosterically activate glycogen synthase. Glycogenolysis Glycogenolysis is the process of glycogen degradation. Glycogenolysis happens in the liver and kidney to produce glucose for balancing the blood sugar; however, it produces G6P in muscle cells to be used as the energy supplier of myocytes.  Activity of the Day Choose one of the Infographic Requirements: Visual Appeal: Use a visually appealing design following carbohydrate- with clear fonts, colors, and images.Content: Title: A catchy and informative title that related illnesses and accurately reflects the topic. research its causes, Introduction: A brief overview of the illness Prevalence and statistics symptoms, and Causes: Explain the underlying causes or risk prevention strategies. Carbohydrate-Related Illnesses: factors. Symptoms: Describe the common symptoms Type 1 Diabetes Then, design and create Type 2 Diabetes experienced by individuals with the illness. Prevention: Discuss preventive measures, such anCeliac infographic Disease that as dietary changes, lifestyle modifications, or clearly Lactoseand concisely Intolerance medical treatments. Treatment: Provide information about available presents this Diseases Glycogen Storage treatment options. Sources: Cite credible sources for your information. information (e.g., medical journals, health organizations).