Presented by :

Dr.Siavash Gerayesh-Nejad

Why Why CarbohydratesCarbohydrates? ?

SugarsSugars Objectives: After studying this session you Objectives: After studying this session you

have to: have to: Define what a carbohydrate molecule is Define what a carbohydrate molecule is Recognise and classify carbohydrate Recognise and classify carbohydrate

moleculesmolecules Explain why carbohydrates are importantExplain why carbohydrates are important Explain different types of isomerism in Explain different types of isomerism in

monosaccharidesmonosaccharides Name other molecules that interact with Name other molecules that interact with

carbohydrates and explain how and why these carbohydrates and explain how and why these interactions occurinteractions occur

Know different names, roles, definitions, Know different names, roles, definitions, structurs and classifications of sugars, MS, structurs and classifications of sugars, MS, OS(DS) & PSOS(DS) & PS

Sugars/ ImportanceSugars/ Importance 11 . .PhotosynthesisPhotosynthesis energy stored in energy stored in

carbohydratescarbohydrates 22 . .The The most abundantmost abundant organic organic

molecules in naturemolecules in nature 33 . .Metabolic precursorsMetabolic precursors of all of all

other biomoleculesother biomolecules 44 . .Central in the metabolismCentral in the metabolism of of

plants and animalsplants and animals 55 . .Important Important structuralstructural component component

of plants (cellulose, pectate), of plants (cellulose, pectate), animals (hyaloronic acid, chitin) animals (hyaloronic acid, chitin) and bacterial cells (murein)and bacterial cells (murein)

Sugars/ ImportanceSugars/ Importance 6. 6. FuelFuel; In animals, they represent a ; In animals, they represent a

major part of the caloric intake.major part of the caloric intake. 7. 7. Energy StorageEnergy Storage ( glycogen, starch, ( glycogen, starch,

inulin).inulin). 8. 8. Cell-cell recognitionCell-cell recognition 9. 9. AdhesionAdhesion (hyaluronic acid) (hyaluronic acid) 10. They are important in 10. They are important in immune immune

responsesresponses either as antigenic either as antigenic determinants or antibody structuredeterminants or antibody structure

11. 11. Protein ageingProtein ageing ( non-enzymatic ( non-enzymatic glycation)glycation)

12. 12. Age determinantAge determinant in some protein in some protein and cells (Asialo glycoprotein)and cells (Asialo glycoprotein)

Sugars/ ImportanceSugars/ Importance

Sugars/ Different names and Sugars/ Different names and definitiondefinition

1- Carbohydrates { Cn(H1- Carbohydrates { Cn(H22O)n }O)n }: : Substances with equal ratio of Substances with equal ratio of carbon atom and water.carbon atom and water.

Exceptions: Exceptions:

*Sugars that have not the formula *Sugars that have not the formula (deoxyribose & Fucose) (deoxyribose & Fucose)

*Substances that are not sugars *Substances that are not sugars but have the formula { but have the formula { formaldehyde formaldehyde (C H(C H22O) & O) & lactic acidlactic acid {C3(H {C3(H22O)3}O)3}

Sugars/ Different names and Sugars/ Different names and definitiondefinition

2- Glucides2- Glucides ( glycos= Gk. sweet) OR ( glycos= Gk. sweet) OR

SaccharidesSaccharides ( sakcharon= Gk. sugar) ( sakcharon= Gk. sugar)

Exceptions:Exceptions:

*Sugars that are not sweet (*Sugars that are not sweet (cellulose cellulose & starch& starch))

*Sweet substances that are not sugars *Sweet substances that are not sugars ((glycerol, monilin, aspartam and glycerol, monilin, aspartam and saccharine)saccharine)

3- Ose3- Ose ( suffix from Fr. sugar) ( suffix from Fr. sugar) 4- Definition:4- Definition: Polyhydroxy compound Polyhydroxy compound

with an aldehyde or a ketone group or with an aldehyde or a ketone group or those compounds that by hydrolysis those compounds that by hydrolysis produce such compounds.produce such compounds.

SugarsSugars Different classifications:Different classifications: 1- With respect to the 1- With respect to the numbernumber of building of building

blocks they are classified into three groups: blocks they are classified into three groups: a-Monosaccharidea-Monosaccharide (mono= (mono= oneone) or ) or

simple sugar have just one unit.simple sugar have just one unit. b-Oligosaccharideb-Oligosaccharide (oligo= (oligo= fewfew) that ) that

are composed of 2-10 Monosaccharide are composed of 2-10 Monosaccharide unitsunits

c-Polysaccharidesc-Polysaccharides (poly = (poly = manymany) are ) are much larger sugars , containing hundreds much larger sugars , containing hundreds of monosaccharide unitsof monosaccharide units

2- With respect being 2- With respect being purepure sugar or having sugar or having other components are classified into:other components are classified into:

a- Glycoproteina- Glycoprotein & & Proteoglycane Proteoglycane bb-- glycolipid and lipopolysccharide glycolipid and lipopolysccharide..

Sugars/General ideaSugars/General idea The The simplestsimplest sugar is sugar is

Glyceraldehyde.Glyceraldehyde. All other simple sugars are All other simple sugars are

derivedderived from Glyceraldehyde. from Glyceraldehyde. The structure of The structure of GlyceraldehydeGlyceraldehyde is is

the basis of sugar classification the basis of sugar classification into two different into two different D or LD or L classes. classes.

They have They have asymmetric (chiral)asymmetric (chiral) carbon. carbon.

The only sugar that has not any The only sugar that has not any

assymetricassymetric carbon is carbon is dihydroxyacetone.dihydroxyacetone. Glucose ( dextrose) is the Glucose ( dextrose) is the reference reference

sugarsugar in medical sciences and is the in medical sciences and is the most most abundantabundant sugar that is present sugar that is present and used as the and used as the fuelfuel in all living in all living organisms.organisms.

Sugars/General ideaSugars/General idea

MS/ Different MS/ Different definitionsdefinitions

They are called simple sugar, because by hydrolysis they can not make any other simpler sugars.

They are called Polyhydroxyaldehyde or Polyhydroxyketone.

In other words:They are Polyhydroxy compound with

an aldehyde or a ketone group.

MonosaccharidesMonosaccharides Different Classifications and Different Classifications and

nomenclatures:nomenclatures:

1- On the basis of the 1- On the basis of the numbers of carbon numbers of carbon atomsatoms: Triose, tetrose, pentose, hexose and : Triose, tetrose, pentose, hexose and heptose.heptose.

2- On the basis of the 2- On the basis of the functional groupfunctional group: : Aldose and ketose.Aldose and ketose. In most cases the name of In most cases the name of a ketose is make by addition of “a ketose is make by addition of “ulul” between ” between the name of sugar and ose. the name of sugar and ose. ExampleExample: Ribose : Ribose and riband ribululose, heptose and heptose, heptose and heptululose.ose.

3-On the basis of 3-On the basis of both above propertiesboth above properties: : Aldotriose, ketotriose.Aldotriose, ketotriose.

MonosaccharidesMonosaccharides Different properties and rolesDifferent properties and roles :: 1- 1- They are composed of 3-7 (3-8) They are composed of 3-7 (3-8)

carbon atomscarbon atoms

2-All are 2-All are solublesoluble, , reducingreducing and easily and easily can make can make crystalcrystal..

3- 3- D- familyD- family sugars are the most sugars are the most abundantabundant sugars in the living sugars in the living organism.organism.

44--Because of the functional groups (Because of the functional groups (aldoaldo, , ketoketo and and hydroxylhydroxyl groups they are groups they are reactivereactive compoundscompounds

6- By becoming cyclic, 5-7 carbon 6- By becoming cyclic, 5-7 carbon sugars are called internal sugars are called internal hemiacetal hemiacetal oror hemiketal. hemiketal. In other words theyIn other words they are referred to those sugars that by are referred to those sugars that by joining of their functional group with joining of their functional group with an hydroxyl group of same molecule.an hydroxyl group of same molecule.

7- By combination they make 7- By combination they make oligooligo and and polysaccharidespolysaccharides..

8-There are different 8-There are different isomerismsisomerisms for for the MSthe MS

MS/ MS/ Different properties Different properties and rolesand roles

MS/ Asymmetric (chiral) MS/ Asymmetric (chiral) carboncarbon

Chiral means Chiral means like hands.like hands.It is referred to a carbon atom It is referred to a carbon atom with with 4 different groups linked 4 different groups linked to it.to it.

Sugars/ General structure/ CyclizationThere are two different

1- methyle glucoside

Monosaccharides Different isomerisms:Different isomerisms:

* Functional* Functional

* Ring* Ring

* Optic* Optic

MS/ isomerisms/MS/ isomerisms/1- 1- FunctionalFunctional

* *AldoseAldose is referred to is referred to those simple sugars those simple sugars that have an that have an aldehyde groupaldehyde group as as their functional their functional groupgroup..

* *KetoseKetose is referred is referred to those simple to those simple sugars that have an sugars that have an ketoneketone group as group as their functional their functional groupgroup..

Aldose to ketose conversion by enediol Aldose to ketose conversion by enediol intermediateintermediate

MS/ isomerisms/Functional

MS/ isomerisms/ 2- Ring

* * By the linking of By the linking of functional group to functional group to a hydroxyla hydroxyl groupgroup, 4-7 carbon sugars , 4-7 carbon sugars make a furan or pyran like rings.make a furan or pyran like rings. In In this way, the carbon ofthis way, the carbon of functional functional group is called group is called anomeric carbon. anomeric carbon.

PyranosePyranose is a six member ring is a six member ring sugar that may be in chair sugar that may be in chair or boat conformation.or boat conformation. FuranoseFuranose is a five member ring is a five member ring sugar that its conformationsugar that its conformation is like a letter envelope.is like a letter envelope. Note that: Note that: Linear and cyclic sugars Linear and cyclic sugars

are isomers.are isomers.

Sugars/ Cyclic (Ring) structure

A: Haworth projection

MS/ Isomerisms / Ring

Furanose/ Pyranose Chair/ Boat

MS/ isomerisms/3- Optic or Steroisomerism

It is because of the presence of It is because of the presence of asymmetric carbon atom and is asymmetric carbon atom and is classified into four types:classified into four types:

* D & L* D & L

* Enantiomerism* Enantiomerism

* Epimerism* Epimerism

* Anomerism* Anomerism

D and L Monosaccharides

The —OH on the chiral atom farthest from the carbonyl group is used to assign the D or L configuration

D

D L

MS/ isomerisms/MS/ isomerisms/StreoisomerismStreoisomerism

1- Optic a- Enantiomerism b- Epimerism c- Anomerism2- Conformational a- Chair b- Boat

* D & L do not refer to the rotation of polarized light, but are stand for the family of the sugar. For showing the rotation of polarized light (+) or (- )sign are used.

* D- family sugars are abundant, natural sugars that are derived from D- glyceraldehyde so the OH group of the last asymmetric atom is at right.

* L- family sugars are rear sugars and just found in the oligosaccharides present as antigenic moieties. They can not be metabolized and make energy. The OH group of the last asymmetric atom is at left..

MS/ isomerisms/3- Optic/ 1- D & L1- D & L

* Definition: * All OH groups have

opposite orientation* A pair of enantiomers have

same name, but are shown with D or L letters .

* They rotate polarized light equally into two opposite directions, if one is D(-) the other one will be L(+).

Example: D(+) Glc & L(-) Glc or D(+)Fru & L(-) Fru

MS/ isomerisms/3- Optic/ 2- Enantiomerism ( mirror image)

Specific rotation of various carbohydrates at 20oC

•D-glucose+52.7•D-fructose-92.4•D-galactose +80.2•L-arabinose+104.5•D-mannose+14.2•D-arabinose-105.0•D-xylose +18.8•Lactose+55.4•Sucrose+66.5•Maltose++130.4•Invert sugar-19.8•Dextrin+195

Definition: The difference Definition: The difference between the between the OH OH orientationorientation of just of just oneone asymmetric carbon atom asymmetric carbon atom other than the last oneother than the last one (the one that determines (the one that determines the family of a sugar).the family of a sugar).

Example: Example: Mannose ( epimer 2 Mannose ( epimer 2

Glc)Glc) Allose ( epimer 3 Allose ( epimer 3

Glc)Glc) Galactose ( epimer 4 Galactose ( epimer 4

Glc)Glc)

MS/ isomerisms/3- Optic/ 3- 3- EpimerismEpimerism

AldosesAldoses

KetosesKetoses

::

Definition:Definition: * * OH orientationOH orientation of of

anomeric carbonanomeric carbon is is the basis of this the basis of this classification. classification.

ββ anomer : Same anomer : Same orientation with the orientation with the side chainside chain

( the last carbon atom)( the last carbon atom) αα anomer : opposit anomer : opposit

orientation with the orientation with the side chainside chain

Example: Example: αα or or ββ anomer of D(+)Glc.anomer of D(+)Glc.

MS/ isomerisms/3- Optic/ 4- 4- AnomerismAnomerism

MS/ isomerisms/ optic / MS/ isomerisms/ optic / MutarotaionMutarotaion

Mutarotaion: Mutarotaion: αα or or ββ anomer can convert to anomer can convert to each other via an open chain intermediate. In each other via an open chain intermediate. In doing so the degree of polarized light rotation doing so the degree of polarized light rotation changes. changes.

At equilibrium 1/3 will be At equilibrium 1/3 will be αα and 2/3 will beand 2/3 will be ββ anomer.anomer.

MS/ Chiral carbon & optic MS/ Chiral carbon & optic isomer numberisomer number

For For each chiraleach chiral center there are center there are two two optic isomers.optic isomers.

They are They are not superimposable.not superimposable. The number of chiral carbon in:The number of chiral carbon in: Linear aldoses: n= N-2 so linear Linear aldoses: n= N-2 so linear

Glc has 2Glc has 244 optic isomers optic isomers Cyclic aldoses: n=N-1 so cyclic Cyclic aldoses: n=N-1 so cyclic

Glc has 2Glc has 255 optic isomers optic isomers Linear ketoses: n= N-3 so linear Linear ketoses: n= N-3 so linear

Fru has 2Fru has 233 optic isomers optic isomers Cyclic ketoses: n= N-2 so cyclic Cyclic ketoses: n= N-2 so cyclic

Fru has 2Fru has 24 4 optic isomers optic isomers

Isomers

Enantiomers

are mirror image

Configurational

Ketose

Steroisomers Same atom

connectivity different arrangement in pace

Functional Isomers different atom

connectivity

Aldose

Conformational

Diasteromers are not mirror image

(epimers)

Boat Chair

Anomers

OPTIC Ring

Furan Pyran

Envelop

Too much …..Carbohydrate will be converted

into fat and stored under the skin leading to weight gain!

THANKST

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