carbohydrates, classification , and its uses .pptx

carbohydrates classification

1. C arbohydrates Anandhi.S

2. VIVEKANANDHA Ms.S.Anandhi Assistant Professor PG & Research Department of Biotechnology Vivekanandha Arts and Science College For Women Sankari ARTS & SCIENCE COLLEGE FOR WOMEN [An ISO 9001:2015 Certified Institution] (Affiliated to Periyar University, Salem Recognised Under Section 2(f) &12(B) of the UGC Act, 1956) Veerachipalayam , Sankari West (Post) – 637 303, Sankari Tk , Salem Dt., Tamil Nadu PG & RESEARCH DEPARTMENT OF BIOTECHNOLOGY

3. OVERVIEW Carbohydrates: The most abundant organic molecules in nature The empiric formula is (CH 2 O)n, “hydrates of carbon” Carbohydrates: provide important part of energy in diet Act as the storage form of energy in the body are structural component of cell membranes Can be cell-surface antigens Can be part of the body’s extracellular ground substance Can be associated with proteins and lipids Part of RNA, DNA, and several coenzymes (NAD+, NADP+, FAD, CoA)

4. OVERVIEW Many diseases associated with disorders of carbohydrate metabolism including: Diabetes mellitus Galactosemia Glycogen storage diseases Lactose intolerance CONT’D

5. CARBOHYDRATES Polyhydroxy aldehydes or ketones, or substances that yield these compounds on hydrolysis Carbohydrate with an aldehyde group: Aldose Carbohydrate with a ketone group: Ketose O H C H- C - OH CH 2 OH CH2OH C O CH2OH Glyceraldehyde Dihydroxyacetone Aldehyde group Keto group

6. General properties of carbohydrates • Carbohydrates act as energy reserves, also stores fuels, and metabolic intermediates. • Ribose and deoxyribose sugars forms the structural frame of the genetic material, RNA and DNA. • Polysaccharides like cellulose are the structural elements in the cell walls of bacteria and plants. • Carbohydrates are linked to proteins and lipids that play important roles in cell interactions . • Carbohydrates are organic compounds, they are aldehydes or ketones with many hydroxyl groups.

7. Biological Importance • Carbohydrates are chief energy source, in many animals, they are instant source of energy. Glucose is broken down by glycolysis/ kreb's cycle to yield ATP . • Glucose is the source of storage of energy. It is stored as glycogen in animals and starch in plants. • Stored carbohydrates acts as energy source instead of proteins. • Carbohydrates are intermediates in biosynthesis of fats and proteins. • Carbohydrates aid in regulation of nerve tissue and is the energy source for brain. • Carbohydrates gets associated with lipids and proteins to form surface antigens, receptor molecules, vitamins and antibiotics. • They form structural and protective components, like in cell wall of plants and microorganisms. • In animals they are important constituent of connective tissues. • They participate in biological transport, cell-cell communication and activation of growth factors. • Carbohydrates that are rich in fibre content help to prevent constipation. • Also they help in modulation of immune system.

8. Isomerism Isomers Compounds having same chemical formula but different structural formula

9. Aldo- Keto Isomers Example: Glucose (Aldose) and Fructose (Ketose)

10. Epimers Epimers CHO dimers that differ in configuration around only one specific carbon atom - Glucose and galactose, C4 - Glucose and Mannose, C2 Galactose and mannose are not epimers

11. Epimerisation When monosaccharides are heated in the basic aqueous solution, the change of stereochemical configuration at a-carbon to C=O group can be seen both in aldose and ketose form. The change can be observed as the removal of hydrogen from α -carbon followed by the protonation of enolate ion. The reprotonation of the intermediate enolate ion on α - carbon gives a mixture of the two epimeric monosaccharides with opposite stereochemical configurations at a-carbon. The phenomenon of the formation of a mixture of epimeric monosaccharides is called epimerisation . For example, in the presence of a base, D-glucose may be converted into D-mannose via the removal of hydrogen at C–2 carbon followed by protonation of the enolate

12. Structures that are mirror images of each other and are designated as D- and L- sugars based on the position of –OH grp on the asymmetric carbon farthest from the carbonyl carbon Majority of sugars in humans are D-sugars Enantiomers (D- and L-Forms)

13. 13 Carbohydrates are designated as D- or L- according to the stereochemistry of the highest numbered chiral carbon of the Fischer projection. If the hydroxyl group of the highest numbered chiral carbon is pointing to the right, the sugar is designated as D ( Dextro : Latin for on the right side ). If the hydroxyl group is pointing to the left, the sugar is designated as L ( Levo : Latin for on the left side ). Most naturally occurring carbohydrates are of the D-configuration.

14. α - and β -Forms Cyclization of Monosaccharides Monosaccharides with 5 or more carbon are predominantly found in the ring form The aldehyde or ketone grp reacts with the –OH grp on the same sugar Cyclization creates an anomeric carbon (former carbonyl carbon) generating the α and β configurations

15. Anomer Anomer is a stereoisomer that mainly exists as a diastereomer . To be more appropriate, its cyclic structure possesses a different configuration only at the hemiketal (having ketone group) or hemiacetal (having aldehyde group) carbon . Hence, this carbon is named an anomeric carbon . The molecule is said to be α - anomer if the structure is comparable to the one in which the hydroxyl group present on the anomeric carbon lies in the axial position of glucose. If the hydroxyl group occupies the equatorial position , then the molecule is known to possess a β - anomer

16. Anomeric forms of fructofuranose are shown to have hydroxyl groups at the axial position ( α - anomer ) and equatorial position ( β - anomer ). Another way to represent the cyclic structure of saccharides is the chair form and boat form (Fig. 1.6). Saccharides in its chair conformation are said to have the lowest energy, whereas boat form is considered to have the highest energy. In chair conformation, the six hydrogens out of 12 are present in equatorial positions, and the other six hydrogens capture the axial position having their C-H bonds in a parallel position concerning each other. The boat form carries two axial 1,4-hydrogen atoms that generate steric strain. Axial position: In this position, there is an imaginary axis that is administered through the cyclic structure, and the sigma bonds lie at the axis parallel to it . Equatorial position: The sigma bonds are subjected to have a perpendicular position with respect to the imaginary axis mentioned above.

17. Haworth projection The Haworth projection derived its name from the English chemist Sir Walter N. Haworth. The following characteristics best describe the Haworth projection. Carbon is an embedded type of atom. There are a total of six carbon atoms in one circle and numbered 1 to 6 . 2. The 1st carbon is called the anomeric carbon. 3 . Hydrogen atoms attached to the carbon atoms are inherent. The presence of the -OH group at the axial position gives α -form , while at the equatorial position, the molecule is considered to have β -form .

18. Mutarotation In solution, the cyclic α and β anomers of a sugar are in equilibrium with each other, and can be interconverted spontaneously Fischer Projection Haworth Projection Fischer Projection

19. Mutarotation Pure α D­ glucose and β D glucose vary from one another in their ability towards the rotation of the planepolarized light. α ­ D­glucose rotates the plane-polarized light by the specific rotation of +112, whereas its β ­ anomer has a specific rotation of 18.7. However, they possess the tendency to quickly convert into a mixture of both the isomers at equilibrium in the aqueous solution. The specific rotation of one form decreases and the other increases i.e., the specific rotation of a solution of α ­D ­(+)­glucose ( mp 146 °C) gradually declines from an initial value of + 112.2° to + 52.7°, while the b­D­ (+)­glucose ( mp 150°C) specific rotation gradually increases from an initial value of + 18.7° to + 52.7°. This change in specific rotation at equilibrium in the aqueous phase is called as mutarotation . The mutarotation can be observed in acid/base catalysis or neutral aqueous solutions at room temperature

20. Sugar Isomers Aldo-keto Epimers D- and L-Forms α - and β -anomers

21. Classification

22. Monosaccharides The monosaccharides commonly found in humans are classified according to the number of carbons they contain in their backbone structures. The word “Monosaccharides” derived from the Greek word “Mono” means Single and “saccharide” means sugar Monosaccharides are polyhydroxy aldehydes or ketones which cannot be further hydrolysed to simple sugar. Monosaccharides are simple sugars. They are sweet in taste. They are soluble in water. They are crystalline in nature. They contain 3 to 10 carbon atoms, 2 or more hydroxyl (OH) groups and one aldehyde (CHO) or one ketone (CO) group.

23. Trioses Trioses are “Monosaccharides” containing 3 carbon atoms. The molecular formula of triose is C3H6O3 Characteristics • Trioses are simple sugars • They are soluble in water • They are sweet in taste. • The triose may contain an aldehyde group ( aldotriose ) or a ketone group ( ketotriose ). Example Glycerose and Dehydroxyacetone

24. Tetroses Tetroses are “Monosaccharides” containing 4 carbon atoms. The molecular formula of tetrose is C4H8O4 Characteristics • Tetroses are simple sugars • Tetroses are soluble in water • They are sweet in taste . • They are crystalline forms. • The tetroses may contain an aldehyde group ( aldotetrose ) or a ketone group ( ( ketotetrose ).

25. Pentoses Pentoses are “Monosaccharides” containing 5 carbon atoms. The molecular formula of Pentose is C5H10O5 Characteristics It is an important component of “nucleic acid”. are simple sugars Pentoses are soluble in water They are sweet in taste and crystalline forms. The pentoses may contain an aldehyde group ( aldopentose ) or a ketone aldotetrose ) or a ketone group

26. Hexoses

27. Monosaccharide Derivatives Sedoheptulose is an additional biologically important carbohydrate that contains 7-carbon atoms The amino sugars are another class of biologically significant carbohydrates that contain nitrogen. These include N- acetylglucosamine ( GlcNAc ): N- Acetylglucosamine (N- AcetylD -Glucosamine, or GlcNAc , or NAG) Systematic name: 2-( Acetylamino )–2-deoxyD-glucose Molecular formula: C8H15NO6 N- acetylgalactosamine ( GalNAc ), N- Acetylgalactosamine ( GalNAc , 2-Acetamido–2-Deoxy-D-Galactopyranose or N-Acetyl-D- Galactosamine ) Systematic name: 2-( Acetylamino )–2-deoxyD-galactose Molecular formula: C8H15NO6 N- acetylneuraminic acid (NANA; also known sialic acid,) Neuraminic Acid & Sialic Acid Systematic name: ( Neuraminic acid) 5-amino– 3,5-dideoxy-D-glycero-D-galacto-non–2- ulosonic acid Molecular formula: C9H17N1 O8 Glucosamine Systematic name: 2-Amino–2-deoxy-D-glucose Molecular Formula: C6H13NO5 2-Amino–2-deoxy-D-glucohexose (C6H13NO5) i

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