1. Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – 422222, India

2. OC-SBT/ SBI/ SGS 031-U01-04 Introduction Programmes and Courses  SEP – SBT031 – Unit 01  SEP – SBI031 – Unit 01  SEP – SGS031 – Unit 01

3. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits  Academic Inputs by Mrs. Rasika Bhore  M.sc ( Microbiology) rasika.bhore@gmail.com

4. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 How to Use This Resource  Counselor at each study center should use this presentation to deliver lecture of 40-60 minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about 40-60 minutes.  Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.  Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.  Appear several times, for all the Self-Tests, available for this course.  Student can use handouts for last minutes preparation just before end exam.

5. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Describe oligosaccharides, mainly disaccharides & trisaccharides. Discuss the reducing & non-reducing sugars. Describe the formation of glycosidic bond between oligosaccharides. Describe various types of glycosidic bonds.

6. School of Science and Technology, Online Counseling Resource… Introduction  An oligosaccharide is a saccharide polymer containing a small number (three to ten)of component sugars, also known as simple sugars.  They are generally found either O- or N-linked to compatible amino acid side chains in proteins or to lipid moieties.  Oligosaccharides are often found as a component of glycoproteins or glycolipids and as such are often used as chemical markers, often for cell recognition.  An example is A and B blood types have two different oligosaccharide glycolipids embedded in the cell membranes of the red blood cells, AB-type blood has both, while O blood type has neither.  Raffinose series, occur as storage or transport carbohydrates in plants. © 2007, YCMOU. All Rights Reserved.6

7. School of Science and Technology, Online Counseling Resource… Oligosaccharides  Oligosaccharides consist of short chains of monosaccharide units (2-10 units) joined together by a glycosidic linkages.  They can be also defined as the compounds (sugars) which gives 2-10 monosaccharides on hydrolysis.  Based on the number of monosaccharide units they are classified into - Disaccharides,Trisaccharides,Tetrasaccharides & so on.  Disaccharides are the most common oligosaccharides found in nature. © 2007, YCMOU. All Rights Reserved.7

8. School of Science and Technology, Online Counseling Resource… 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. © 2007, YCMOU. All Rights Reserved.8

9. School of Science and Technology, Online Counseling Resource… Formation of Glycosidic Bond The anomeric hydroxyl and a hydroxyl of another sugar or some other compound can join together, splitting out water to form a glycosidic bond: R-OH + HO-R'  R-O-R' + H 2 O E.g., methanol reacts with the anomeric OH on glucose to form methyl glucoside (methyl- glucopyranose). © 2007, YCMOU. All Rights Reserved.9

10. School of Science and Technology, Online Counseling Resource… α- 1,4 Glycosidic Bonds  An α-glycosidic bond for a D-sugar emanates below the plane of the sugar while the hydroxyl (or other substituent group) on the other carbon points above the plane (opposite configuration).  Maltose, is a disaccharide with an α(1-4) glycosidic linkage between the C1 hydroxyl of one glucose and the C4 hydroxyl of a second glucose. Maltose is the α anomer, because the O at C1 points down from the ring. © 2007, YCMOU. All Rights Reserved.10

11. School of Science and Technology, Online Counseling Resource… β-1,4 Glycosidic Bonds  β-glycosidic bond emanates above that plane (the same configuration).  Cellobiose, is the otherwise equivalent ß anomer. The configuration at the anomeric C1 is ß (O points up from the ring). The ß(1-4) glycosidic linkage is represented as a "zig- zag" line, but one glucose residue is actually flipped over relative to the other. © 2007, YCMOU. All Rights Reserved.11

12. School of Science and Technology, Online Counseling Resource… 1,4 & 1,6 Glycosidic Bonds  In a 1,4-glycosidic bond a C1-O-C4 bond is made involving the C1 of one sugar molecule and C4 of the other; likewise a C1-O-C6 bond is called a 1,6-glycosidic bond.  E.g- Amylopectin α(1,6) linkage is denoted in blue colour. © 2007, YCMOU. All Rights Reserved.12

13. School of Science and Technology, Online Counseling Resource… Alpha & beta Linkages  These α, β, linkages may also located between the C 1 (or C 2 ) of one sugar residue and the C 1, C 2, C 3, C 4, C 5 or C 6 of the second residue, depend on which the disaccharides can be classified.  A branched sugar results if more than two types of linkage are present in single molecule. © 2007, YCMOU. All Rights Reserved.13

14. School of Science and Technology, Online Counseling Resource… Disaccharides  Disaccharides consist of two monosaccharides units.  They are crystalline, water soluble & sweet to test.  Sucrose, Maltose & lactose are the most physiologically important disaccharides.  They are sub classified on the basis of the presence or absence of free reducing group (aldehyde or ketone) & the type of linkages. © 2007, YCMOU. All Rights Reserved.14

15. School of Science and Technology, Online Counseling Resource… Classification of Disaccharides Disaccharides are classified as: Non- reducing Trehalose (C1-C1) Sucrose (C1- C2) ReducingC1-C4: Lactose Maltose Cellobiose C1-C6 Isomaltose Gentiobiose meliobiose © 2007, YCMOU. All Rights Reserved.15

16. School of Science and Technology, Online Counseling Resource… Reducing Sugars  A sugar, that has the property of reducing various inorganic ions, notably cupric ion to cuprous ion.  A sugar can act as a reducing sugar, when one of the disaccharide units has free anomeric carbon i.e. not involved in the glycosidic bond. © 2007, YCMOU. All Rights Reserved.16

17. School of Science and Technology, Online Counseling Resource… Lactose  Lactose (4-O-β-D-galactopyranosyl-D-glucose):  It is the predominant disaccharide found in milk. In Lactose intolerance, malabsorption of lactose leads to diarrhea & flatulence.  Galactosaemia is a condition that results from an inability to metabolize D- galactose. © 2007, YCMOU. All Rights Reserved.17

18. School of Science and Technology, Online Counseling Resource… Maltose  Maltose (4-O-α-D-glucopyranosyl-D-glucose) results from hydrolysis of starch by enzymes (amylases) in the mammalian digestive tract.  Maltose is used as a sweetener and as a substrate for fermentation.  It is also the constituent of the polymer amylose. © 2007, YCMOU. All Rights Reserved.18

19. School of Science and Technology, Online Counseling Resource… Cellobiose  Cellobiose (4-O-β-D-glucopyranosyl-D-glucose) results from the hydrolysis of cellulose by bacteria. Mammals lack the necessary enzymes—cellobiohydrolases and endo- cellulases to hydrolyze cellulose.  Cellobiose constitutes materials such as cotton and paper. Maltose is a homopolmyer of cellobiose. © 2007, YCMOU. All Rights Reserved.19

20. School of Science and Technology, Online Counseling Resource… Isomaltose  Isomaltose (6-O-α-D-glucopyranosyl-D-glucose) is formed from two glucose monosaccharides.  It is often found at the branching points of amylopectin and glycogen.  It is hydrolyzed to glucose in the intestinal tract by an enzyme called isomaltase. Gentiobiose Gentiobiose (6-O-β-D-glucopyranosyl-D-glucose) is found in many glycosides such as amygdaline. © 2007, YCMOU. All Rights Reserved.20

21. School of Science and Technology, Online Counseling Resource… Non-Reducing Sugars  These are the sugars which cannot reduce inorganic ions such as cupric or ferric.  This is due to the absence of free anomeric carbon i.e. the anomeric carbon of both the disaccharide units are involved in glycosidic bond. © 2007, YCMOU. All Rights Reserved.21

22. School of Science and Technology, Online Counseling Resource… Sucrose  Sucrose (β-D-fructofuranosyl α-D- glucopyranoside) is the predominant disaccharide found in sugar cane and sugar beet.  It is a well known sweetener and has a five member furanosyl unit. 108 tons of sucrose are produced annually for consumption. © 2007, YCMOU. All Rights Reserved.22

23. School of Science and Technology, Online Counseling Resource… Trehalose  Trehalose (α-D-glucopyranosyl α-D- glucopyranoside) is found in microbes, fungi, and certain insects.  One isomer is neotrehalose with an α,β link.  Another isomer is isotrehalose which has a β,β link. © 2007, YCMOU. All Rights Reserved.23

24. School of Science and Technology, Online Counseling Resource… Trisaccharides  Trisaccharides are oligosaccharides composed of three monosaccharides.  Examples include: Acarbose Raffinose Melezitose © 2007, YCMOU. All Rights Reserved.24

25. School of Science and Technology, Online Counseling Resource… Raffinose  Raffinose is a trisaccharide composed of galactose, fructose and glucose.  The raffinose family of oligosaccharides (RFOs) are α- galactosyl derivatives of sucrose, and the most common are the trisaccharide. © 2007, YCMOU. All Rights Reserved.25

26. School of Science and Technology, Online Counseling Resource… Occurrence of Raffinose  It can be found in beans, cabbage, sprouts, asparagus, other vegetables, and whole grains.  Raffinose can be hydrolyzed to D-galactose and sucrose by the enzyme α- galactosidase (α-GAL), an enzyme not found in humans.  RFOs are almost ubiquitous in the plant kingdom, being found in a large variety of seeds and they rank second only to sucrose in abundance as soluble carbohydrates. © 2007, YCMOU. All Rights Reserved.26

27. School of Science and Technology, Online Counseling Resource… What we learn………………  Oligosaccharides are two or more sugar units linked together.  Glycosidic bonds formed when anomeric hydroxyl & another hydroxyl group is joined.  1,4 α & β, as well as 1,6 α & β glycosidic linkages are formed.  Among disaccharides, sucrose is non-reducing sugar while lactose, maltose is reducing sugar.  Raffinose is found in grains, beans etc & not hydrolyzed by human. © 2007, YCMOU. All Rights Reserved.27

28. School of Science and Technology, Online Counseling Resource… Critical Thinking Questions  Where reducing sugars are useful? why? © 2007, YCMOU. All Rights Reserved.28

29. School of Science and Technology, Online Counseling Resource… Hints To Critical Thinking Question  In biochemical tests.  They having reducing property. © 2007, YCMOU. All Rights Reserved.29

30. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.30 Study Tips  Book 1 Title: Biochemistry Author: Lubert Stryer  Book 2 Title: A guidebook to biochemistry Author: Michael Yudkin

31. School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.31 Study Tips www.en.wikipedia.org Microsoft Encarta Encyclopedia www.ull.chemistry.com Carbohydrates www.web.indstate Biochemistry of carbohydrates

32. End of the Presentation Thank You !