Carbohydrate Chemistry Part 1 PDF

BIOCHEMISTRY FOR MEDICAL LABORATORY SCIENCE Carbohydrate Chemistry Part 1 Doc Les INTRODUCTION TO CARBOHYDRATES  It is a polyhydroxy aldehydes or polyhydroxy ketones  Carbohydrates is a broad group of biological substances that includ...

BIOCHEMISTRY FOR MEDICAL LABORATORY SCIENCE Carbohydrate Chemistry Part 1 Doc Les INTRODUCTION TO CARBOHYDRATES  It is a polyhydroxy aldehydes or polyhydroxy ketones  Carbohydrates is a broad group of biological substances that include  Polyhydroxy means that each of the carbon atoms (C) contains your “monosaccharides, oligosaccharides and polysaccharides as well as hydroxyl group (OH) substances derived from monosaccharides.”  They may or may not follow the empirical formula: (CH2O)n GENERAL STRUCTURE  Sugar – applied to monosaccharides and some oligosaccharides  Every carbon (C) contains your hydroxyl group (OH) depending where it is written, either from the left or the right. With the MEDICALLY SIGNIFICANT FUNCTIONS OF CARBOHYDRATES exception of the carbon that is double bonded with your oxygen (O) A. Broken down to yield ATP, the biological energy fuel for all living systems. Oxidation of 1 g of Carbohydrate will yield 4 kcal of energy. Protein and Fats yield 4 kcal and 9 kcal per gram respectively B. Serve as intermediates for the biosynthesis of biochemical entities The picture above is termed as your Carbonyl Group. It is a such as fats and proteins carbon that is double bonded to your oxygen C. Associated with other entities such as glycosides, vitamins and antibiotics  The position of the carbonyl group will determine the functional D. They serve as precursors for DNA, RNA and ascorbic acid synthesis group of your carbohydrates The sugar in DNA = deoxyribose The sugar in RNA = ribose E. They form structural tissues in plants and in microorganism Examples: o Cellulose in plants o Chitin in insects o Peptidoglycan in bacteria o Hyaluronic acid as ground substance in connective tissue of vertebrates.  If the carbonyl group is under C1 it is termed as an Aldose Sugar F. Participate in biological transport, regulatory functions in cell-cell  If the carbonyl group is under C2 it is termed as a Ketose Sugar recognition Glycoprotein transport molecules like transferrin for iron STRUCTURAL REPRESENTATION OF CARBOHYDRATES transport and ceruloplasmin for copper transport Straight Chain Configuration Fischer Projection Carbon chain is written vertically with C1 G. Activation of growth factors and modulation of the immune system at the top which is the carbonyl group Glycoprotein enzymes like pepsin, DNASe and hormones like FSH (C=O) if an aldose or the carbon furthest and TSH above the carbonyl group if a ketose H. Function for protection If the carbon is attached to four different Mucin found in mucus groups, it is called an asymmetric or chiral carbon, a site of stereoisomerism I. Contribute to the basis of blood typing Type A – N-acetylgalactosamine (GalNAc) The carbon in the carbonyl group is also Type B – D-galactose called the anomeric carbon. It is the Type AB – both sugar are present carbon that is attached to an oxygen. Type O – both sugar are absent Note that the C should be attached to an O only and NOT to an OH (this is a CARBOHYDRATES hydroxyl)  Is made up of three different components: Carbon, Hydrogen & Oxygen The highest numbered chiral carbon or  It is the most important source of energy for the body the last chiral carbon is called the penultimate carbon  Most important carbohydrate in the body is glucose (C6H12O6)  Three major classes of carbohydrates: If the OH in the penultimate carbon o Monosaccharides- 1 sugar only project to the right, the sugar is in the D o Disaccharides- more than 2 sugars configuration. If it projects to the left, the o Polysaccharides- more than 10 sugars sugar is in the L configuration  Is all about HYDRATES of carbon. Hydrates because it has a water and it is made up of carbon. It is where carbohydrate is derived 1 BIOCHEMISTRY FOR MEDICAL LABORATORY SCIENCE Carbohydrate Chemistry Part 1 Doc Les Example of Fischer Ring: Example of Chiral or Asymmetric Carbon: To be a chiral carbon, the carbon must be In this picture, we name this attached to 4 different groups. carbohydrate as ketohexose because it has 6 carbons and its carbonyl group is at C2. In this example, the ⋆ represents the chiral carbons. So in total there are 4 chiral carbons Next, its configuration is at here. Why is C1 not a chiral carbon? C1 is not the D-form since the OH group a chiral carbon because there is a double of the penultimate is positioned bond with O meaning there is symmetry in at the right. the bonds (having 2 O). C6 is also not a chiral carbon because it has 2 H attached to it Now, to determine the α and ß form, we look at C2 (since it’s a ketose) and check where the OH is positioned. If it’s at the Ring Configuration left, then it is in ß form and α Haworth Projection A flat (planar) structure lying form if the OH is at the right. perpendicular to the plane of the paper with the thickened line closest to the reader So we name the carbohydrate at the left as ß-D-ketohexose and α-D- ketohexose for the carbohydrate at the right. Only possible for sugars with 5 or more carbons Naming of Carbohydrates Rule: May assume a 5-member furanose 1. Identify the placement of carbonyl group to know whether if it is an or 6-member pyranose ring. 99% of aldose or a ketose Glucose exist in the pyranose form 2. Know the number of carbon atoms it contains. The number of carbon atoms is used in the suffix of carbohydrate naming (table shown C1 is the carbon immediately to the below) right of the oxygen atom or the 3. Lastly add –ose at the suffix of the number of carbon. carbon farthest to the right o Example: -triose The -H, -OH, and CH2OH groups # of Carbon atoms Suffix project either above or below the 2 -di plane. This corresponds to the left 3 -tri and right configuration in the 4 -tetra straight chain formula respectively. 5 -penta Down – Right. Up – Left 6 -hexa Most aldohexoses are six- membered Examples of Carbohydrate Naming: Aldotetroses, Aldopentoses, Ketohexoses are 5-membered Pyran rings are 6-membered Furan rings are 5-membered The carbons are numbered clockwise starting with the carbon immediately to the right of oxygen Name: Aldopentose (O). Name: Ketopentose 2 BIOCHEMISTRY FOR MEDICAL LABORATORY SCIENCE Carbohydrate Chemistry Part 1 Doc Les For D-sugars the last carbon is drawn above the plane. For L-sugars, the last carbon is drawn below the plane In this projection, the carbon that previously configured the carbonyl group now becomes attached to four different groups and therefore becomes an asymmetric or chiral carbon If the OH group at the anomeric carbon is drawn opposite the projection of the last carbon, the sugar is in the α form If the OH group at the anomeric carbon is projected in the same side as the projection of the last carbon, it is in the ß form. 62% of glucose exist in the ß form Ring Configuration Newman/Conformational Chair The configuration that best Form represents the three-dimensional conformation of sugars with 5 or more carbons actually existing in solution ISOMERISM Isomers are compounds with the same chemical formula but differ in spatial configuration. The presence of asymmetric or chiral carbons allow the formation of isomer. A. D/L isomerism: look at the structural representation below. They are also called enantiomers or mirror images of each other B. Epimers: stereoisomers that differ only in configuration about ONE chiral carbon with the D-glucose as reference. Two major aldohexose in nature, glucose and galactose, are epimers at C4. Glucose and mannose are C2 epimers 3 BIOCHEMISTRY FOR MEDICAL LABORATORY SCIENCE Carbohydrate Chemistry Part 1 Doc Les 4