L1 CHO Chemistry PDF

Carbohydrate chemistry  Prof.Fagr Bazeed Ass.Prof. Ghada Helal “I”  Contents Definition, Biological importance and General classification of Carbohydrates. Monosaccharides: Definition. Classification. Structural composition with examples. Existence and biologi...

Carbohydrate chemistry  Prof.Fagr Bazeed Ass.Prof. Ghada Helal “I”  Contents Definition, Biological importance and General classification of Carbohydrates. Monosaccharides: Definition. Classification. Structural composition with examples. Existence and biological importance of monosaccharides. By the end of this lecture, the students should be able to: 1. Define Carbohydrates: mono, di, and polysaccharides. 2. Classify carbohydrates. 3. Identify the different types and functions of monosaccharides, disaccharides and polysaccharides. 4. Summarize the biological importance of different types of carbohydrates 5. Correlate their knowledge to a clinical situation PART 1 § Monosaccharides  CASE SCENARIO q Hossam is a 45 years old male patient, presented to emergency room (ER) with complaints of fatigue, dizziness, pale skin, sweating, headache and rapid heartbeats. The patient blood pressure was 110/70 mmHg, His random blood sugar was 49 mg/dl.  Definition: Carbohydrates are Organic compounds characterized by 3 features: Containing :.Containing more Containing free than one “OH” active carbonyl (C, H & O). group group Carbon (Poly–hydroxyl) Either aldhyde Hydrogen, (HC=O) or Oxygen ketone (C=O) group Why we study C H O § C H O is the primary source for production of energy for tissues e. g. brain, muscles and erythrocytes. § Is there any other functions of CHO? Function of Carbohydrates: -They serve as energy stores and fuels. -They share in the cell membranes structure. -Pentose sugars (ribose and deoxyribose) contributes in the structure of nucleic acids. -They share in the structure of glycoproteins and glycolipids. -They play important roles in cell recognition.  Classification of Carbohydrates SUGAR UNITS 1) Simple carbohydrates 2) Complex carbohydrate Monosaccharides Disaccharides Oligosaccharides Polysaccharides 1 sugar unit 2 sugar unit 3-10 sugar units > 10 sugar units Glucose, fructose, Maltose, Raffinose, sesamose Starch, glycogen, galactose sucrose, lactose fibers  Monosaccharides Definition Classification Biological importance Monosaccharides’derivatives  Definition of monosaccharides They are the simplest sugar : 1. Formed of one sugar unit 2. cannot be hydrolyzed into smaller units Classification of monosaccharides Monosaccharides are further classified according to: Number of C atom Active sugar gp ØTrioses: 3 carbon atoms. Aldehyde: (aldoses) ØTetroses: 4 carbon atoms. (H-C=O) ØPentoses: 5 carbon atoms. ØHexoses: 6 carbon atoms Ketone:(Ketoses). (C=O)  (6 carbons) Hexoses (aldhyde group) (ketone group) Aldoses Ketoses Naming of Sugar: D vs. L Name according to penultimate carbon as compared to D-glyceraldehyde Cyclization of Sugars C1 is anomeric carbon C1 condenses with O5 to form intramolecular hemiacetal Fischer projection “right” on Fischer = “down” on Haworth Haworth projections  = -OH down (right)  = -OH up (left) Monosaccharides of Biological Importance Type Biological importance 1-Glucose 1. Principal famous sugar in the blood. (Dextrose or 2. Primary source for energy for tissues e. g. brain and Grape Sugar) erythrocytes. 3. Ingested carbohydrates are absorbed in the form of glucose. 4. It can convert to other sugars like: galactose, lactose, fructose, ribose, glycogen. Where/why?? 2-Fructose 1.It is the sugar of seminal plasma (sperms utilize fructose for energy production). 1. It enters in the formation of: a) disaccharide sucrose b) polysaccharideinulin  Monosaccharides of Biological Importance Type Biological importance 3-Galactose It enters in the formation of a)Lactose (milk sugar): in mammary gland b) Galactolipids & glycoproteins. 4-Pentoses Enter in the formation of:- (e.g. ribose) a. Nucleic acids: RNA b. Energy compound: ATP. c. Co-enzymes :NAD & NADP d. 2nd messenger : cAMP e. Vitamins: riboflavin 5-Mannose Enter in the formation of glycoproteins  Monosaccharides Derivatives ✓ They are substances that are derived from monosaccharides ✓ Includes 1. Sugar acids 3. Deoxy sugar 2. Sugar alcohols 4. Amino sugars Derivative Results of Clinical importance 1- Sugar Due to Oxidation of monosaccharides Oxidation of glucose by Glucose acids: ✓ Oxidation of the carbonyl group gives oxidase is the principle of measuring aldonic acid. the amount of glucose in urine and in a) Aldonic Glucose oxidase blood using test strips. acids Eg: Glucose Gluconic acid b) Uronic acids ✓ Oxidation of the last carbon gives Glucuronic acid is used in uronic 1.Formation of mucopolysaccharides 2.Detoxification and excretion of certain substances. Eg: Glucose D glucuronic acid  Monosaccharides Derivatives cont. Derivative Results of Clinical importance 2-Sugar ✓ Reduction of mono-saccharides. 1.Glucose à Sorbitol, alcohols 2.Mannoseà Mannitol, 3.Galactoseà Galactitol (Dulcitol). (Alditols) 4.Fructoseà Sorbitol or Mannitol. 3-Deoxy- ✓one OH group is replaced by H at C-2 2-Deoxy-ribose is a constituent of (1 oxygen is missed ) DNA sugars: Eg. 2-Deoxy-ribose 4-Amino- ✓ OH group is replaced by an Amino sugars are found in amino group at the C-2 position. sugars: glycosaminoglycans and e.g. glucosamine and glycoproteins galactosamine.  Case Report and Clinical Correlates -The case represents symptoms of hypoglycemia (dizziness, fatigue, pale skin, headache, sweating and rapid heartbeats). -The patient blood pressure was 110/70 mmHg, the random blood sugar was 49 mg/dl. -Some cells and tissues, including brain and erythrocytes, depend on glucose because they cannot oxidize alternative fuels. -Therefore, the body maintains a blood glucose level of 70–110 mg/dl at all times.  §Disaccharides PART 2 §Polysaccharides Disaccharides Definition Classification  Definition of Disaccharides Disaccharides consist of 2 monosaccharide units joined by an O-glycosidic bond. Classification of Disaccharides Homodisaccharides: Heterodisaccharides: formed of the same monosaccharide e.g. formed of different monosaccharide units maltose, isomaltose and cellobiose. e.g. sucrose and lactose The most abundant disaccharides are sucrose, maltose, and lactose  Definition of Disaccharides Disaccharides consist of 2 monosaccharide units joined by an O-glycosidic bond. Classification of Disaccharides 1) Homodisaccharides: 2) Heterodisaccharides: formed of the same formed of different monosaccharide monosaccharide units e.g. e.g. maltose, isomaltose and e.g. sucrose and lactose cellobiose.  1.HOMODISACCHARIDES Maltose (malt sugar) Isomaltose Cellobiose Structure Two α-glucose units Two α-glucose units Two units β glucose Bond α 1-4 glycosidic α 1-6 glycosidic β 1-4 glycosidic Reduction Reducing sugar Reducing sugar Reducing sugar Source From starch by the Hydrolysis of some Acid hydrolysis of action of amylase polysaccharides such cellulose enzymes as dextran. 2.HETERODISACCHARIDS Disaccharide Sucrose Lactose (milk sugar) Structure α-glucose and β-fructose β-galactose and β-glucose Bond α-1- β-2 glycosidic bond β 1-4 with free (involving the anomeric Cs) anomeric C. It is a reducing sugar non reducing sugar (presence of free active Reduction (no free active carbonyl carbonyl group) group) Source Fruits and vegetable principal carbohydrate in milk The most abundant disaccharides are sucrose, maltose, lactose  Polysaccharides Definition Classification Biological importance Definition of polysaccharides Polysaccharides, also called glycans, consist of more than 10 monosaccharide units and/or their derivatives joined together by glycosidic linkage. Classification of polysaccharide Homopolysaccharides Heteropolysaccharides (homoglycans): (heteroglycans): contain only one type of contain more than one type of monosaccharide. E.g. starch, glycogen, monosaccharides. E.g.glycosaminoglycans dextrin, cellulose, inulin (GAGs, mucopolysacchrides), 1. HOMOPOLYSACCHARIDES Disaccharide 1-Starch 2-Glycogen (animal starch) Structure It is formed of α- glucose units It is formed of α-glucose units consists of 2 layers: It is highly branched molecule 1. Inner linear non branching layer called amylose. 2. Outer highly branched layer called amylopectin. Function 1. It is the most common storage 1. The major form of storage polysaccharides in animals and human polysaccharide in plants body. 2. Acts as a basic source of energy (more 2. It is found mainly in liver (about 10% of than half of C H O taken by human are liver mass) and skeletal muscle (about starch. 1 to 2 % of muscle mass). In fasting: breakdown of glycogen to maintain blood glucose level during fasting STARCH G LYC O G EN 1.HOMOPOLYSACCHARIDS CONT. 3-Dextrin 4-Cellulose Structure Several α -glucose units Several β- glucose units. linked by α 1-4 linkage, and the link α 1-6 at the branching point Function Dextrin is used Most abundant natural polymer found in 1. As mucilage 2. in infant feeding the world. It is the structural component of the cell walls of nearly all plants. Cellulose is not digested in human due to absence of B glucosidase en z yme à increase bulk of food in intestine à increase peristalsisà prevent constipation??? application 2. HETEROPOLYSACCHARIDES Other names: =Glycosaminoglycans (GAGs) =Mucopolysaccharides Structure of G AG s : long linear unbranched chains composed of a repeating disaccharide unit (sugar acids-amino sugar)n. 1. The am ino sugar: (glucosam ine or galactosamine) 2. The sugar acid: e.g. glucuronic aci d  TYPES OF HETEROPOLYSACCHARIDES (GAGS) Type Site Main function 1-Heparin Intracellular GA Gs Anticoagulant 2 Heparan sulfate Extracellular G AG Component of cell surface 3Hyaluronic acidSynovial fluid of joints lubricant and shock absorbent 4Keratan sulfate cornea, cartilage 5-Chondroitin cartilage, tendons, ligaments Protective and supportive sulfate 6-Dermatan bone, skin, blood vessels sulfate q Chatterjea’s Textbook of Medical Biochemistry, 8th edition. q Vasudevan's Textbook of Biochemistry For Medical Students, 6th Edition. q Lippincott’s Illustrated Reviews: Biochemistry, 8th edition.