Carbohydrates PDF

Republic of the Philippines WESTERN MINDANAO STATE UNIVERSITY COLLEGE OF MEDICINE If it is a terminal is an aldehyde, it is an aldose. Zamboanga City ALDOSE...

Republic of the Philippines WESTERN MINDANAO STATE UNIVERSITY COLLEGE OF MEDICINE If it is a terminal is an aldehyde, it is an aldose. Zamboanga City ALDOSE BIOCHEMISTRY MODULE Functional group is an aldehyde (C=OH) Prepared by: FARR KRIZHA TANGKUSAN, RN, MD Carbonyl carbon at the end Examples: glucose, galactose, mannose CARBOHYDRATES ▪ Cn(H2O)n – “hydrate of carbon” ▪ Aldehyde or ketone derivatives of polyhydric alcohols ▪ Saccharide – “sugar” FUNCTIONS OF CHO: ✓ Major source of energy (glucose) - 1 g CHO = 4 kcal ✓ Storage form of energy = glycogen If it is not terminal, then there is a ketone and is ✓ Important structural components designated as ketose. ✓ (membranes, cell walls, genetic codes) - Cellulose (cell walls of plants), KETOSE proteoglycans, chitin Functional group is a ketone (C=O) ✓ Cell-to-cell interaction Carbonyl carbon at any other position ✓ Act as lubricants and transporters Example: fructose ✓ Confer specificity to cells (blood types) ✓ Components of hormones, enzymes, nucleic acids CHEMISTRY OF MONOSACCHARIDES ✓ Isomers - Compounds of same formula but different structures - Glucose, fructose, galactose, and mannose are all isomers of one - another because they have the same CLASSIFICATIONS OF CHO: formula C6H12O6 1. Monosaccharides – “simple sugars” - Ex: C6H12O6 - glucose and fructose 2. Disaccharides – “mono- + mono-” 3. Oligosaccharides – 3-10 units of mono- ✓ Epimers 4. Polysaccharides – >10 units of mono- - Isomers that differ in configuration around only one specific carbon atom *Monosaccharides: monomeric units of (except the carbonyl carbon) carbohydrates *The sugar units are linked together by glycosidic bonds MONOSACCHARIDES ▪ “Simple sugars” – cannot be hydrolyzed further ▪ Classified: o Ketoses or aldoses o Based on # of carbons Examples: glucose and galactose (differ only in position of –OH in C4); glucose and mannose (differ only in position of –OH in C2) ✓ D- and L- Isomerism - based on spatial orientation of glycerose ✓ Enantiomers - isomers that are mirror images of each other  - The enantiomers are designated as a D- POLYSACCHARIDES sugar (Dextrorotatory) - and an L-sugar (Levorotatory) ✓ Condensation of > 10 monosaccharide units - D-sugars are more common ✓ Branched or linear ✓ Examples: Starches, dextrin, glycogen, cellulose, inulin ▪ Amylose: α-1,4 ▪ Amylopectin and glycogen: α-1,4 and α-1,6 ▪ Inulin: used in GFR determination → not hydrolyzed in the body ▪ Cellulose: constituent of plant cell walls → adds bulk to diet (fiber) TYPES OF POLYSACCHARIDES: 1. Homopolysaccharides [homoglycans] - contain 1 type of sugar unit - Ex. starch, glycogen, cellulose, inulin 2. Heteropolysaccharides [heteroglycans] ✓ Anomers - contain more than 1 type of sugar unit - In aqueous solutions, monosaccharides - Ex. Heparin, hyaluronic acid, with five or more carbon atoms in the chondroitin sulfate backbone occur predominantly as cyclic (ring) structures. STARCH - Ex: Furanose: monosaccharide structure with a Five-membered - ring; Pyranose: monosaccharide structure with a six-membered ring - Rotation around the carbonyl carbon produces anomers, which are labeled α and β anomers COMPONENTS OF STARCH ✓ Amylose (< 20%) – linear chain of glucose units linked by α-1,4 bond REMEMBER: ✓ Amylopectin (> 80%) – branched chains Isomers are molecules with same chemical linked by α-1,4 bonds with α-1,6 bond every formula but differ in structure. 24 to 30 residues Epimers-kapag same na same itchura pero GLYCOGEN na-iba lang position ng OH sa - Highly branched isang carbon. - Consists of glucose units linked by α-1,4 bonds with α-1,6 (branching point) Enantiomers-Mirror images, naflip lahat ng every 8 to 12 residues position ng OH. Anomers: naiba position ng OH sa anomeric carbon, alpha pag asa baba ung OH, beta pag nasa taas ung OH ng anomeric C. MNEMONIC: “Be-Taas, A-baba” DISACCHARIDES DERIVED CARBOHYDRATES: ✓ Condensation of 2 monosaccharides units ▪ Obtained from chemical reactions ✓ Examples: Lactose, maltose, sucrose 1) Oxidation product [sugar acids – glucoronic acid] OLIGOSACCHARIDES 2) Reduction product [sugar alcohol – mannitol] ✓ Condensation of 3-10 monosaccharide units ✓ Most are not digested by humans  3) Amino sugars [Ex. glucosamine, GLYCOPROTEINS galactosamine] - (also known as mucoproteins) are 4) Deoxysugars [Ex. D-2 deoxyribose] proteins containing branched or unbranched oligosaccharide chains PHYSIOLOGICALLY IMPORTANT - With carbohydrate content < 10% CARBOHYDRATES: GLYCEMIC INDEX - Measure of digestibility of a carbohydrate - Based on extent to which the CHO raises the blood glucose concentration compared with an equivalent amount of glucose or a reference food Glucose, galactose, lactose, isomaltose, trehalose – index of 1 (or 100%) Sucrose, fructose, sugar alcohols – less than 1 Starch – variable index (from 0-1) Nonstarch polysaccharides – index of 0 REDUCING SUGARS ▪ Presence of free –C=O → acts as reducing agent ✓ All monosaccharides are reducing sugars ✓ Nonreducing sugars: sucrose, trehalose GLYCOSAMINOGLYCANS ▪ Reacts with several reagents - Mucopolysaccharides → amino acids ✓ Benedict’s reagent → (+) brick red and uronic acids precipitate (Copper) - Provide ground or packing substance of ✓ Fehling’s test → same principle with connective tissues Benedict’s - Examples: Hyaluronic acid, chondroitin ▪ Application: detection of sugars in urine SO4, heparin *SUMMARY*  Carbohydrates are major constituents of animal food and animal tissues. They are characterized by the type and number of monosaccharide residues in their molecules.  Glucose is the most important carbohydrate in mammalian biochemistry because nearly all PROTEOGYLCANS carbohydrate in food is converted to glucose for - Carbohydrate chains attached to a metabolism. polypeptide chain.  The physiologically important monosaccharides include glucose, the “blood sugar,” and ribose, an important constituent of nucleotides and nucleic acids.