Biochemistry - Carbohydrate Structure PDF

1A BIOCHEMISTRY STRUCTURE of CARBOHYDRATES DR. BRENDO JANDOC # of Carbons...

1A BIOCHEMISTRY STRUCTURE of CARBOHYDRATES DR. BRENDO JANDOC # of Carbons Generic names Examples I. OVERVIEW 3 Trioses Glyceraldehyde  Carbohydrates are the most abundant organic molecules 4 Tetroses Erythrose in nature 5 Pentoses Ribose  Carbohydrates exist in 2 forms: polyhydroxylated 6 Hexoses Glucose aldehydes and polyhydroxylated ketones 7 Heptoses Sedoheptulose  Carbohydrates are compounds that contain at least 3 9 Nonoses Neuraminic acid carbon atoms, hydroxyl group, and usually an aldehyde or ketone group.  Disaccharides contain 2 monosaccharides  Carbohydrates may contain phosphate, amino or sulphate  Oligosaccharides contain 3-10 monosaccharides  Phosphate groups (UDP-glucose)  Polysaccharides contain >10 monosaccharides  Amino groups (Glucosamine & Galactosamine)  Aldoses are carbohydrates with an aldehyde as their most  Sulfate groups (Chondroitin sulphate and other oxidized functional group. Ex: Glyceraldehyde Glycosaminoglycans)  Ketoses are carbohydrates with a keto group as their most  (CH2O)n oxidized functional group. Ex: Dihydroxyacetone  Hydrate of carbon  Functions:  provides significant fraction of energy  storage form of energy in the body Pentoses Source Importance  as metabolic intermediates D-Ribose Nucleic acid Coenzymes, Pentose  comprise large portions of nucleotides that form Phosphate Pathway DNA and RNA (PPP)  cell membrane components that mediate some D-Ribulose Metabolic PPP forms of intercellular communication processes  lubrication D-Arabinose Gum arabic, Plum Glycoproteins  immunity and Cherry gums  structural component of many organisms D-Xylose Wood gums, Glycoproteins (bacterial cell wall, exoskeleton of many insects, Proteoglycans, fibrous cellulose of plants) Glycosaminoglycans  Monosaccharides aka Simple sugars can be classified D-Lyxose Heart muscle Constituent of according to the number of carbons they contain Lyxoflavin  Monosaccharides are linked by Glycosidic bonds L-Xylulose Uronic Acid Pentosuria  Phosphorylation is the initial step in sugar metabolism Pathway  Glucosamine is the product of chitin hydrolysis and is the major polysaccharide of the shells of insects and Hexoses Source Importance crustaceans D-Glucose Fruit juices; Glycosuria,  Galactosamine can be found in in polysaccharide of Hydrolysis of starch, Hyperglycemia cartilage, chondroitin sulphate cane sugar, maltose,  N-Acetylneuraminic Acid is an important constituent of lactose glycoproteins composed of an acetylated amino sugar, D-Fructose Fruit juices, honey, Changed to glucose Nacetylmannosamine, covalently linked to pyruvic acid cane sugar, inulin, in the liver;  Glycosyltransferases are enzymes that establish natural Jerusalem artichoke Hereditary fructose glycosidic linkages intolerance leads to  Glycogen is the major storage form of carbohydrates in fructose animals accumulation and  Largest stores are in muscle and liver Hypoglycemia  Liver glycogen is used to maintain blood glucose during D-Galactose Hydrolysis of lactose; Changed to glucose fasting or exercise mammary gland in the liver; Failure to  Muscle glycogen is used to generate ATP for muscle metabolize leads to contraction Galactosemia and  Sugar Acids are produced by oxidation of the aldehydic Cataract carbon, the hydroxyl carbon, or both ex. Ascorbic Acid D-Mannose Plant mannans and (Vitamin C), Glucuronic Acid gums  Glucuronic Acid is a component of proteoglycans and is involved in bilirubin metabolism  Deoxy Sugars possess a hydrogen atom in place of 1 of Isomers and Epimers their hydroxyl groups ex. 2-deoxyribose (DNA)  Sugar Alcohols are monosaccharides (aldoses, ketoses)  Isomers/Stereoisomers are compounds that have the reduced at the carbonyl carbon same chemical formula but have different structures Ex. Fructose, Glucose, Mannose, Galactose with a chemical formula of C6H12O6  1A BIOCHEMISTRY STRUCTURE of CARBOHYDRATES DR. BRENDO JANDOC  Epimers are stereoisomers that differ in the position of the  Starch (Amylose + amylopectin) - plant sources hydroxyl group at only one asymmetric carbon Ex. Glucose  Cellulose - plant sources & Galactose are C-4 epimers  Glycosaminoglycans Enantiomers Complex carbohydrates  Enantiomers are special type of isomerism that is found in  Complex carbohydrates are carbohydrates attached to the pairs of structures that are mirror images of each non-carbohydrate structures other  Example of these non-carbohydrate structures are  2 members of the pair are designated as D- and L- sugar  Purine & pyrimidine bases (Nucleic acid)  Dextrorotatory (D) refers to the polarized light is rotated  Aromatic rings (Steroids & Bilirubin) to the right (clockwise)  Proteins (Glycoproteins & Glycosaminoglycans  Levorotatory (L) refers to the plane of polarized light  N-glycoside refers to the structure wherein the –NH2 rotated to the left (counterclockwise) group in the non-carbohydrate molecule is attached to the  Majority of sugars in humans are D-sugars sugar ex. Nucleotides  Racemases are enzymes that are able to interconvert D-  O-glycoside refers to the structure wherein the –OH group and L- isomers in the non-carbohydrate molecule is attached to the sugar ex. Disaccharides, Oligosaccharides, Polysaccharides Blood Group Antigens Cyclization of monosaccharides  Blood Group Antigens are specific classes of oligosaccharides that may be bound to proteins, lipids &  Although monosaccharides are often drawn as straight membrane surfaces chains (Fischer projections), they exist mainly as rings  ABO antigens are distinguished by a different single-sugar (Haworth projections) moiety on a common oligosaccharide core  Monosaccharides are predominantly found in a ring or  Blood Types: A, B, AB, O cyclic form  Variable residue 