Carbohydrates Structure and Function PDF

Carbohydrates Metabolism Carbohydrates Structure and Function Structure Function Glycolysis and the Pentose Phosphate Pathway Introduction and Preparatory Phase Payoff Phase, Regulation and Fate of Pyruvate Gluconeogenesis Precursors, Entry Points and Bypass Reactions Regulation...

Carbohydrates Metabolism Carbohydrates Structure and Function Structure Function Glycolysis and the Pentose Phosphate Pathway Introduction and Preparatory Phase Payoff Phase, Regulation and Fate of Pyruvate Gluconeogenesis Precursors, Entry Points and Bypass Reactions Regulation Glycogen Metabolism and Regulation of Carbohydrate Metabolism Glycogen Breakdown Glycogen Synthesis 1 In This Learning Objectives: Explain the chemical logic associated with the Section… reaction of glycolysis and gluconeogenesis. Describe the purpose and interpret the results of all biochemical reactions of glycolysis, gluconeogenesis and glycogen metabolism Connect concepts and summarize information related to regulation of carbohydrate metabolism Recognize the connections between signal transduction, metabolism, and health Suggested Reading: Chapters 14 and 15 Supplemental Content: Solved Problems Deeper Dives 2 Carbohydrates Structure and Function 3  Important Terms and Concepts Anomeric carbon Reducing sugars Non-reducing sugars Adolse Ketose Pyranose Furanose Hemiacetal/hemiketal Glycosidic bond (α and β) Glycogen Cellulose Monosaccharides Disaccharides Polysaccharides Sucrose Lactose Maltose 4 Background 5  Carbohydrates Functions Polymer Type Repeating unit Size (number of Roles/significance monosaccharide units) Starch: Homo- (𝛼𝛼1→4)Glc, 50-5,000 Energy storage: in plants Amylose linear Starch: Homo- (𝛼𝛼1→4)Glc, Up to 106 Energy storage: in plants Amylopectin with (𝛼𝛼1→6)Glc branches every 24-30 residues Glycogen Homo- (𝛼𝛼1→4)Glc, Up to 50,000 Energy storage: in bacteria and animal with (𝛼𝛼1→6)Glc cells branches every 8-12 residues Cellulose Homo- (𝛽𝛽1→4)Glc Up to 15,000 Structural: in plants, gives rigidity and strength to cell walls Chitin Homo- (𝛽𝛽1→4)GlcNAc Very large Structural: in insects, spiders, crustaceans, gives rigidity and strength to exoskeletons Dextran Homo- (𝛼𝛼1→6)Glc, Wide range Structural: in bacteria, extracellular with (𝛼𝛼1→3) adhesive branches Peptidoglycan Hetero-; peptides 4)Mur2Ac(𝛽𝛽1→4) Very large Structural: in bacteria, gives rigidity attached GlcNAc (𝛽𝛽1 and strength to cell envelope Hyaluronan (a glycosaminoglycan) Hetero-; acidic 4)GlcA(𝛽𝛽1→3) Up to 100,000 Structural: in vertebrates, extracellular GlcNAc (𝛽𝛽1 matrix of skin and connective tissue; viscosity and lubrication in joints 6  Classification of Carbohydrates Monosaccharides: simple sugars, consist of a single polyhydroxy aldehyde or ketone unit - example: D-glucose Disaccharides: oligosaccharides with two monosaccharide units: example: sucrose (D-glucose and D-fructose) Oligosaccharides: short chains of monosaccharide units, or residues, joined by glycosidic bonds Polysaccharides: sugar polymers with 10+ monosaccharide units: examples: cellulose (linear), glycogen (branched) Source: https://www.researchgate.net/figure/Classification-of-carbohydrates-and-examples-of-compounds- belonging-to-each-group-dashed_fig1_342969912 7 Monosaccharides 8 Important Monosaccharide Structures 9  Properties of Monosaccharides Colorless crystalline solid Freely soluble in water Insoluble in non-polar solvents Unbranched carbon chains Common mono- and disaccharides names end in “-ose” 10 Stereochemistry of Monosaccharides 11 D-Aldoses 12 D-Ketoses 13 Epimers 14 Cyclization 15 Conformations of β-D-Glucose 16 Pyranoses and Furanoses 17 Glycosidic Bonds 19 Disaccharides 20 Disaccharides This Photo by Unknown author is licensed under CC BY. 21 Three Common Disaccharides Subunits? Linkage? Reducing or Non-reducing? 22 Polysaccharides 23 Homopolysaccharides and Heteropolysaccharides 24 Storage Polysaccharides Glycogen 25 Structural Polysaccharides 26 Derivatives and Glycoconjugates 28 Derivatives 29 Glycoproteins 30 Blood Group Antigens 31  Summary Carbohydrates (or saccharides) are compounds with the stoichiometric formula (CH2O)n or derivatives of such compounds. Their oxidation provides a major source of energy. Because of their multiple chiral centers, these saccharides exist as enantiomeric pairs (D and L) of multiple diastereomers. Monosaccharides can either be aldoses or ketoses. Those containing five or more carbons exist mainly in the form of rings of five (furanoses) or sic (pyranoses) atoms (heterocyclic), resulting for internal hemiacetal (or hemiketal) formation. Such rings exist as α or β anomers and exhibit multiple conformations. Derivatives of monosaccharides include phosphate esters, acids, and lactones, amino sugars and glycosides. Phosphate esters are important as metabolic intermediates; glycosides represent a large class of compounds formed by elimination of water between a sugar and another hydroxy compound. Oligosaccharides and polysaccharides are formed by making glycosidic links between monosaccharides. Polysaccharides serve multiple functions – energy storage, structure roles, and identification/recognition. The blood group antigens are an example of the identification/recognition function. Complex glycan chains are assembled by stepwise transfer of monosaccharide units from nucleotide-linked sugars, through the action of glycosyltransferases. 32