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3 simple and complex carbohydrates lec 3


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3 simple and complex carbohydrates lec 3

  1. 1. Principle of Biochemistry 3-Simple and Complex Carbohydrates Course code: HFB324 Credit hours: 3 hours Dr. Siham Gritly Dr. Siham Gritly 1
  2. 2. Terms should be learned vocabulary• Carbohydrate; generic name for simple and complex sugars; chemically carbohydrates are polyhydroxyl aldehydes or polyhydroxyl ketones• Aldose; sugar containing an aldehyde functional group• Ketose; sugar containing a ketone functional group• anomeric carbon; the carbon atom in a cyclic monosaccharide which, in the linear monosaccharide, holds the aldehyde or ketone functional group Dr. Siham Gritly 2
  3. 3. vocabulary• Asymmetric carbon; carbon atoms attached to four different atoms or groups or chiral carbon• Chiral carbon; atoms have four different atoms or groups covalently attached to them -linked sugars; refers to;(a) the geometry of the glycosidic bond (α = opposite side of the sugar ring from the free CH2OH; β = same side),(b) which carbon on ring A is linked to which carbon on ring B.• Stereoismers; are compounds having two or more chiral carbons that have the same four groups attached to carbon atoms but are not mirror images to each other• D-sugar; the stereoisomeric form of monosaccharide. One of a set of isomers whose molecules have the same atoms bonded to each other but differ in the way these atoms are arranged in space. Dr. Siham Gritly 3
  4. 4. vocabulary• Furanose; cyclic form of glucose monosaccharide whose structure is a five-membered ring• Pyranose; cyclic form of glucose; monosaccharide in a six- membered ring form• glycosidic bond; ether bond joining two monosaccharides• hemiacetal or hemiketal; cyclic conformation of simple carbohydrates; formed by reaction of the aldehyde (or ketone) and one of the hydroxyls on the carbohydrate Dr. Siham Gritly 4
  5. 5. vocabulary• Monosaccharides. "Simple sugars" with the formula (C H2O)n. The word carbohydrate refers to the fact that this class of molecules consists of hydrates of carbon.• Disaccharides; "Simple sugars" contain two monosaccharides units attached to one another through acetal bonds or as known glycosidic bonds• Oligosaccharides. complex sugar Polymeric molecule of sugar comprising 2-10 covalently linked monosaccharide units. Often found conjugated to other classes of biomolecules including lipids and proteins.• Polysaccharides. complex sugar Larger polymers of simple sugars. On the order of hundreds to thousands of monosaccharide units as linear or branched polymers Dr. Siham Gritly 5
  6. 6. vocabulary• Aldehyde ; Any of a class of highly reactive organic chemical compounds obtained by oxidation of primary alcohols, characterized by the common group CHO, and used in the manufacture of dyes, and organic acids.• Aldehydes are oxidized to carboxylic acids and take part in many addition reactions• ketone Any of a class of organic compounds, such as acetone, having a carbonyl group linked to a carbon atom in each of two hydrocarbon radicals and having the general formula R(CO)R ,• Ketones dont have that hydrogen atom and are resistant to oxidation. They are only oxidised by powerful oxidising agents which have the ability to break carbon-carbon bonds. Dr. Siham Gritly 6
  7. 7. Dr. Siham Gritly 7
  8. 8. Carbohydratesare polyhydroxy aldehydes or ketones (Constructed from the atoms of carbon, oxygen and hydrogen)• In aldehydes (aldose) the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains. Formula H- (CHOH)x(C=O)-• In ketones (Ketoses) carbonyl group (C= O) is bonded to two carbons within a carbon skeleton Dr. Siham Gritly 8
  9. 9. In aldehydes (aldose) the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains. H-(CHOH)x(C=O)- easily oxidized In ketones (ketose) carbonyl group (C= O) is bonded to two carbons within a carbon skeleton no hydrogen atom H H | | H—C—C—C—H | " | H O H H H H | | |H—C—C—C=O | | H H Glycerildyhide Dr. Siham Gritly 9
  10. 10. • The major carbohydrates found in the body are structurally related to the;-• 1-aldotriose glyceraldehyde• 2-ketotriose dihydroxyacetone.• All carbohydrates contain at least one asymmetrical (chiral) carbon and are, therefore, optically active. Dr. Siham Gritly 10
  11. 11. Aldotriose and ketotriose glyceraldehyde is especiallyimportant because the more complex monosaccharides may be considered to be derived from them Dr. Siham Gritly 11
  12. 12. Carbohydrate Nomenclature• Monosaccharide• Disaccharides,• Oligosaccharides• Polysaccharides Dr. Siham Gritly 12
  13. 13. Monosaccharides• The common monosaccharides (hexoses) of living organisms are:• (glucose, galactose, fructose) C₆H₁₂O₆• (ribose, deoxyribose, ribulose, xylose) 5- carbon pentoses (C5H10O4).• Contain 3-7 carbon atoms.(trioses, tetroses, pentoses, hexoses and heptoses)• Contain hydroxyl groups -OH• Carbonyl group C=O Dr. Siham Gritly 13
  14. 14. • The 5-carbon monosaccharide ribose is an important component of;-• - coenzymes (e.g., ATP, FAD, NAD)• - the backbone of the genetic molecule RNA• Deoxyribose which is a component of DNA• Dr. Siham Gritly 14
  15. 15. glucose is the most important monosaccharide Ketoses contain a ketoneAldoses contain an aldehyde (C=O) functional group(-CHO ) functional groupat usually at C #2. e.g. fructoseone end e.g. glucose Dr. Siham Gritly 15
  16. 16. the nomenclature and functional group for monosaccharidesNumber of Carbons Aldose (Generic Ketone Functional Functional Relevant examples monosaccharide Group Group name) 3 Ketotriose Glyceraldehyde, Aldotriose (Triose) Triulose Dihydroxyacetone 4 Ketotetrose Aldotetrose Erythrose (Tetrose) Tetrulose 5 Ketopentose Ribose, Ribulose, Aldopentose (Pentose) Pentulose Xylulose 6 Ketohexose Glucose, Galactose, Aldohexose (Hexose) Hexulose Mannose, Fructose Dr. Siham Gritly 16
  17. 17. Conformation of monosaccharidestrioses, tetroses, pentoses, hexoses Dr. Siham Gritly 17
  18. 18. Stereochemistry Isomerism• Stereochemistry deals with arrangements of atoms in molecules and the effects of these arrangements on the chemical and physical properties of substances• Isomerism are compound have the same structural formula but differ in configuration• The presence of asymmetric carbon or chiral (carbon atoms attached to four different atoms or group) allows the formation of isomer• Different groups are attached it is easy to move any two or groups of atoms to other position and rotate the new structure Dr. Siham Gritly 18
  19. 19. D and L isomerism• Organic substances usually are optically active• The presence of asymmetric carbon atoms give optical activity on the compound• If Plane-polarized light is passed through a solution of the substances, ;-the plane of light is rotated to• - the right (dextrorotary substances)• -or to the left (for levorotatory )• expressed as• *dextrorotary (D)• *levorotary (L) Dr. Siham Gritly 19
  20. 20. • The direction and extend of the rotation of a particular compound depend on;• -concentration of the substances• -temperature• -wave of the light• Enzyme function specify the particular configuration such as L-glutamate dehydrogenase Dr. Siham Gritly 20
  21. 21. The majority of saccharides in nature have the "D" isomer Fischer projection Haworth Projection of β- D-Glucose The orientation of the –H and –OH groups around the carbon atom adjacent to terminal alcohol carbon (CH2OH) carbon 5 determine whether the sugar is D or L isomer Dr. Siham Gritly 21
  22. 22. Haworth Projection of α- and β D-GlucoseIn α-D-glucose the anomeric carbon’s –OH group is on theright. In the Haworth projection of α-D-glucose illustratedbelow the –OH group points down and β D glucose OHpointed up. Dr. Siham Gritly 22
  23. 23. Cyclic Fischer Projection of α-D-GlucoseIn cyclic structure or Fisher projection the anomeric hydroxyl are positioned to right resulting in alpha configuration Cyclic Fischer Projection of α-D- Glucose Dr. Siham Gritly 23
  24. 24. Ring and chair configuration of glucose Dr. Siham Gritly 24
  25. 25. aldose-ketose isomerism• The carbonyl group of the keto or aldose functional group is considered to be closest to the "start" of the carbon chain.• The carbon thus identified as the "first" carbon in the chain is carbon #1. The remaining carbons are numbered sequentially.• In Fischer Projections, the "D" isomer will have the hydroxyl (-OH) functional group located on the right-hand side of the chiral C. Dr. Siham Gritly 25
  26. 26. Fischer projection of glyceraldehyde AldotrioseD,L designation refers to the configuration the highest-numbered asymmetric center Dr. Siham Gritly 26
  27. 27. Fischer projections for some aldotetroses Dr. Siham Gritly 27
  28. 28. • aldotetroses: – Carbon 1 is at the end closest to the aldehyde carbonyl – Carbon 3 is the highest numbered carbon that is chiral (carbon 4 is not chiral because it contains two hydrogens) – The "D" or "L" nomenclature therefore refers to the chirality of carabon 3. The "D" form has the OH group on the right-hand side of carbon 3; the "L" form has the OH group on the left-hand side. – Carbon 2 is chiral, and the different isomers of this aldotetrose are indicated by different common names Dr. Siham Gritly 28
  29. 29. Fischer projections for some ketopentoses Dr. Siham Gritly 29
  30. 30. ketopentoses• Carbon 1 is the end closest to the keto group• Carbon 4 is the highest chiral carbon and determines the "L" or "D" isomer nomenclature for the saccharide• Carbon 3 is also chiral, and its chirality determines the common name• Carbon 2 is not chiral, neither is carbon 1, or carbon 5. Dr. Siham Gritly 30
  31. 31. Cyclic monsaccharide structures and anomeric forms α and β anomers• Ring structure of CHO• In solution the molecules cyclize by a reaction between carbonyl group and hydroxyl group• If the sugar contain an aldehyde it is called hemiacetal• If the sugar contain a keto group it is called hemiketal• In cyclic structure or Fisher projection the anomeric hydroxyl are positioned to right resulting in alpha configuration• If the anomeric hydroxyl are positioned to left the structure would be in beta configuration Dr. Siham Gritly 31
  32. 32. • The resulting chirality of the aldehyde carbon (or keto carbon in ketoses) in the cyclic structure can be either the α- or β- form. This carbon is termed the anomeric carbon, and the α - and β - forms are anomers. Dr. Siham Gritly 32
  33. 33. pyranose and furanose ring structures• "Pyranose" is used to refer to the pyran ring structure (6-membered ring with 5 carbons and 1 oxygen) Cyclic sugars that contain a six membered ring are called "pyranoses• For five membered rings (four carbons and 1 oxygen) the structure is a furanose ring. Cyclization is reversible Dr. Siham Gritly 33
  34. 34. Cyclic form of glucose is a pyranoseCyclic form of fructose is a furanose• The pyranose ring is formed by the reaction of the hydroxyl group on carbon 5 (C-5) of a sugar with the aldehyde at carbon 1.• This forms an intramolecular hemiacetal.• If reaction is between the C-4 hydroxyl and the aldehyde, a furanose is formed hemiketal.• The pyranose form is more stable than the furanose form, Dr. Siham Gritly 34
  35. 35. • glucose forms an intra-molecular hemiacetal by reaction of the aldehyde on C1 with the hydroxyl on C5, forming a six-member pyranose ring, named after the compound pyran Dr. Siham Gritly 35
  36. 36. The furanose and pyranose forms of D-glucoseThe furanose forms of D-glucose The pyranose forms of D-glucosefour carbons and 1 oxygen 6-membered ring with 5 carbons and 1 oxygen Dr. Siham Gritly 36
  37. 37. glucopyranose The ring structure representations of "Haworth Projections“The pyranose ring is formed by the reaction of the hydroxylgroup on carbon 5 (C-5) of a sugar with the aldehyde at carbon1. This forms an intramolecular hemiacetal Dr. Siham Gritly 37
  38. 38. chair configuration of the glucopyranose ringchair configurationThe α and β anomers of glucose chair form.the position of the hydroxyl group (red or green) on theanomeric carbon relative to the CH2OH group bound to carbon5: they are either on the opposite sides (α), or the same side (β). Dr. Siham Gritly 38
  39. 39. mutarotation of glucose ringsTwo ring forms of glucose differ in whether the hydroxyl group attached tocarbon number 1 is fixed below (alpha glucose ) or above (beta glucose ) A change in the specific optical rotation of light that takes place in the solutions of freshly prepared sugars; Carbohydrates can change spontaneously between the α and β configurations: a process known as mutarotation. α and β configurations Found in equilibrium and spontaneously are interconverted (mutarotation Dr. Siham Gritly 39
  40. 40. Pentose sugar ribose• Ribose is an organic compound with the formula C5H10O5• Ribose constitutes the backbone of RNA, a biopolymer that is the basis of genetic transcription• Once phosphorylated, ribose can become a subunit of ATP, NADH, important in metabolism Dr. Siham Gritly 40
  41. 41. Riboseis an aldopentose (a five-carbon aldehyde) Dr. Siham Gritly 41
  42. 42. Deoxyribose• deoxyribose, also called d-2-deoxyribose, five- carbon sugar component of DNA (deoxyribonucleic acid), where it alternates with phosphate groups to form the “backbone” of the DNA polymer and binds to nitrogenous bases.• The presence of deoxyribose instead of ribose is one difference between DNA and RNA (ribonucleic acid). Dr. Siham Gritly 42
  43. 43. Deoxyribose replacement of the hydroyl group at the C2position with hydrogen, leading to the net loss of an oxygen deoxy. Dr. Siham Gritly 43
  44. 44. Disaccharides• Disaccharides; contain two monosaccharides units attached to one another through acetal bonds or as known glycosidic bonds• Covalent bonds between the anomeric hydroxyl of a cyclic sugar and the hydroxyl of a second sugar (or another alcohol containing compound) are termed glycosidic bonds, and the resultant molecules are glycosides.• The linkage of two monosaccharides to form disaccharides involves a glycosidic bond. Several physiogically important disaccharides are sucrose, lactose and maltose Dr. Siham Gritly 44
  45. 45. Glycosidic bond• Glycosidic bond are formed between hydroxyl group of one monosaccharide and hydroxyl group of the next with the removal of water• Glycosidic bonds involve the hydroxyl group of the anomeric carbon (keto or aldehyde) of one member of the pair of monosaccharide and hydroxyl group on carbon 4 or 6 of the second member Dr. Siham Gritly 45
  46. 46. • Glycosidic bond can be α or β• Glycosidic bonds may be designated• - α 1-4, β 1-4, α 1-6 and so on• Important disaccharides are• 1-maltose• 2-lactose• 3-sucrose Dr. Siham Gritly 46
  47. 47. Lactose. This disaccharide is comprise of a galactose linked toglucose via a β-1-4 glycosidic bond. "Milk sugar" - it is theprinciple carbohydrate of milk. Must be broken down intogalactose and glucose by the enzyme lactase. Dr. Siham Gritly 47
  48. 48. Sucrose. This disaccharide is glucose-α-1,2-fructose."Table sugar". No free anomeric carbon, therefore, nota reducing sugar. Dr. Siham Gritly 48
  49. 49. Maltose. This disaccharide is glucose-α-1,4 glucose."Grain sugar". Formed from the partial hydrolysis ofstarch. Has a free anomeric carbon and is therefore areducing sugar. Dr. Siham Gritly 49
  50. 50. Complex carbohydrates• When polysaccharides are composed of a single monosaccharide building block, they are termed homopolysaccharides example starch and glycogen.• Polysaccharides composed of more than one type of monosaccharide are termed heteropolysaccharides, give sugar andnon-sugar like SO4 or NH4 gp e.g.glycosaminoglycans ( found in connective tissue)heparin present in mast cells as anticoagulant Dr. Siham Gritly 50
  51. 51. polysaccharides; consist of many mono-saccharides. the mainmonosaccharide found in polysaccharides is D-glucose. Polysaccharides of nutritional important are Dr. Siham Gritly 51
  52. 52. Polysaccharides Glycogen1- Glycogen • Made and found in human bodies • Glycogen is the major form of stored carbohydrate in animals. Stored in liver and muscle • This vital molecule is a homopolymer of glucose in α–(1,4) linkage • Glycogen is a very compact structure that results from the coiling of the polymer chains • Not found in plants • Saved for later use; the liver contain enzyme which convert glycogen to glucose through the process known as glycogenlysis. Dr. Siham Gritly 52
  53. 53. Glycogen Dr. Siham Gritly 53
  54. 54. 2-Starch is a storage polysaccharide composed of glucose monomers• Its structure is identical to glycogen, Starch -- 2 forms: • amylose: linear polymer of α(1-> 4) linked glucose residues • amylopectin: branched polymer of α(1-> 4) linked glucose residues with α(1-> 6) linked branches Dr. Siham Gritly 54
  55. 55. • starch; occur mainly in plant kingdom. Important sources are cereals, millets, roots, tubers formed in nature in large amounts.• Starch hydrolyzed by amylase enzyme present in saliva and in pancreatic juice to form maltose (disaccharide).• during hydrolysis starch formed intermediate product called dextrin. complete digestion of starch formed glucose;• starch--------dextrin----------maltose------------glucose Dr. Siham Gritly 55
  56. 56. Starch forms amylose Dr. Siham Gritly 56
  57. 57. amylopectin Dr. Siham Gritly 57
  58. 58. • 3-Dietary fiber is a carbohydrates (or a polysaccharide) that is incompletely absorbed in humans and in some animals.• *Dietary fiber consists mainly of cellulose, a large carbohydrate polymer that is indigestible because humans do not have the required enzymes to digest it. There are two subcategories: soluble and insoluble fiber. Whole grains, fruits (especially plums, and figs) and vegetables are good sources of dietary fiber. Dr. Siham Gritly 58
  59. 59. CelluloseCellulose in fibers is also a polymer of glucose monomers ,but using beta rings (1-4 bond) Dr. Siham Gritly 59
  60. 60. Dr. Siham Gritly 60
  61. 61. Polysaccharide Functions• Polysaccharides functions related to• storage,• structure• protection.• Energy Dr. Siham Gritly 61
  62. 62. Carbohydrates metabolism Dr. Siham Gritly 62
  63. 63. Diseases associated with Carbohydrates• Diabetes mellitus• Galactosemia• Glycogen storage diseases• Lactose intolerance Dr. Siham Gritly 63
  64. 64. References• Murry K. Robert, Granner K. daryl, Mayes A. peter, Rodwell W. Victor (1999). Harpers Biochemistry. Appleton and Lange , twent fifth edition• Campbell, Neil A.; Brad Williamson; Robin J. Heyden (2006). Biology: Exploring Life. Boston, Massachusetts: Pearson Prentice Hall• A. Burtis, Edward R. Ashwood, Norbert W. Tietz (2000), Tietz fundamentals of clinical chemistry• Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 52–59• Maitland, Jr Jones (1998). Organic Chemistry. W W Norton & Co Inc (Np). p. 139. ISBN 0-393-97378-6.• Nelson DL, Cox MM (2005). Lehningers Principles of Biochemistry (4th ed.). New York, New York: W. H. Freeman and Company.• Matthews, C. E.; K. E. Van Holde; K. G. Ahern (1999) Biochemistry. 3rd edition. Benjamin Cummings.• Dr. Siham Gritly 64
  65. 65. • Sareen Gropper, Jack Smith and James Groff, Advanced Nutrition and Human Metabolism, fifth ed. WADSWORTH• Melvin H Williams 2010; Nutrition for Health, Fitness and Sport. 9th ed, McGraw Hill•• Heymsfield, SB.; Baumgartner N.; Richard and Sheau-Fang P. 1999. Modern Nutrition in Health and Disease; Shils E Maurice, Olson A. James, Shike Moshe and Ross A. Catharine eds. 9th edition• Guyton, C. Arthur. 1985. Textbook of Medical Physiology. 6th edition, W.B. Company Dr. Siham Gritly 65
  66. 66. • Lehninger. Principles of bochemistry. by Nelson and Cox, 5th Edition; W.H. Freeman and Company• Emsley, John (2011). Natures Building Blocks: An A-Z Guide to the Elements (New ed.). New York, NY: Oxford University Press. ISBN 978-0-19-960563-7.• Koppenol, W. H. (2002). "Naming of New Elements (IUPAC Recommendations 2002)" (PDF). Pure and Applied Chemistry 74 (5): 787–791. doi:10.1351/pac200274050787. 7.pdf. Dr. Siham Gritly 66