18-1 Chemistry 121 Winter 2009 LA Tech Introduction to Organic Chemistry and Biochemistry Instructor...

18-1Chemistry 121 Winter 2009 LA Tech

Introduction to Organic Chemistry and BiochemistryIntroduction to Organic Chemistry and Biochemistry Instructor Dr. Upali Siriwardane (Ph.D. Ohio State) E-mail: [email protected] Office: 311 Carson Taylor Hall ; Phone: 318-257-4941;Office Hours: MTW 9:00 am - 11:00 am; TR 9::00 - !0:00 am & 1:00-2:00 pm.December 19, Test 1 (Chapters 12-14)January 2 Test 1 (Chapters 15-16)February 6 (Chapters 17-19)February 27, (Chapters 20-22)March 2, 2009, Make Up Exam:Bring Scantron Sheet 882-E

Chemistry 121(01) Winter 2009


Chapter 18:Chapter 18:Carbohydrates Carbohydrates

Sections


Chapter 18: Chapter 18: CarbohydratesCarbohydrates18.1 Biochemistry--An Overview18.2 Occurrence and Functions of Carbohydrates18.3 Classification of Carbohydrates18.4 Chirality: Handedness in Molecules18.5 Stereoisomerism: Enantiomers and Diastereomers18.6 Designating Handedness Using Fischer Projections18.7 Properties of Enantiomers18.8 Classification of Monosaccharides18.9 Biochemically Important Monosaccharides18.10 Cyclic Forms of Monosaccharides18.11 Haworth Projection Formulas18.12 Reactions of Monosaccharides18.13 Disaccharides18.14 General Characteristics of Polysaccharides18.15 Storage Polysaccharides18.16 Structural Polysaccharides18.17 Acidic Polysaccharides18.18 Glycolipids and Glycoproteins18.19 Dietary Considerations and Carbohydrates


BiochemistryBiochemistryBiochemistryBiochemistry is the study of the chemical processes in is the study of the chemical processes in

living organisms. It deals with the structure and function living organisms. It deals with the structure and function of cellular components, such as proteins, carbohydrates, of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules.lipids, nucleic acids, and other biomolecules.

• Carbohydrates • Lipids • Proteins • Nucleic Acids • Use of carbohydrates as an energy source


Occurrence and Functions of CarbohydratesOccurrence and Functions of Carbohydrates

OccurrenceOccurrenceDifferent objects such as sheets of paper, insect skeletons, Different objects such as sheets of paper, insect skeletons,

fruits, cotton fabrics and ropes have one common feature: fruits, cotton fabrics and ropes have one common feature: they all contain carbohydrates.they all contain carbohydrates.

FunctionsFunctionsThe chemical structure of carbohydrates, with their many The chemical structure of carbohydrates, with their many

hydroxyl groups and the ability to assumehydroxyl groups and the ability to assume

various spatial configurations, makes it possible for them to various spatial configurations, makes it possible for them to form nearly unlimited combinationsform nearly unlimited combinations

with other carbohydrate molecules, as well as with proteins with other carbohydrate molecules, as well as with proteins and lipids. The resulting structuresand lipids. The resulting structures

perform important biological functions.perform important biological functions.


Classification of Carbohydrates MonosaccharidesMonosaccharidesThey consist of one sugar containing They consist of one sugar containing 3,4,5,6 and 7 carbon atoms 3,4,5,6 and 7 carbon atoms and are and are

usually colorless, water-soluble, crystalline solids. Some usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides monosaccharides have a sweet taste. Examples of monosaccharides include include glucose (dextrose), fructose (levulose), galactose, xylose and glucose (dextrose), fructose (levulose), galactose, xylose and ribose. ribose.

Disaccharides Disaccharides a sugar (a carbohydrate) composed of two monosaccharides.a sugar (a carbohydrate) composed of two monosaccharides.

OligosaccharideOligosaccharide An oligosaccharide is a saccharide polymer containing a small number

(typically 3-10 monosaccharides

PolysacharidesPolysacharidesAre relatively complex carbohydrates. They are polymers made up of Are relatively complex carbohydrates. They are polymers made up of

many monosaccharides joined together by glycosidic bonds. They many monosaccharides joined together by glycosidic bonds. They are insoluble in water, and have no sweet taste. are insoluble in water, and have no sweet taste.


Chirality: Handedness in MoleculesChirality: Handedness in Molecules

A "chiral" molecule is one that is not superimposable with its mirror image. Like left and right hands that have a thumb, fingers in the same order, but are mirror images and not the same, chiral molecules have the same things attached in the same order, but are mirror images and not the same.


Fischer Projection FormulasFischer Projection FormulasFischer projection:Fischer projection: a two dimensional a two dimensional

representation for showing the configuration of a representation for showing the configuration of a tetrahedral stereocentertetrahedral stereocenter• horizontal lines represent bonds projecting forward • vertical lines represent bonds projecting to the rear• the first and last carbons in the chain are written in full;

others are indicated by the crossing of bonds

CHO

CH OH

CH2OH

CHO

H OH

CH2OH

(R)-Glyceraldehyde

convert to a Fischerprojection

(R)-Glyceraldehyde


Stereoisomerism: Enantiomers and DiastereomersStereoisomerism: Enantiomers and DiastereomersA Fischer projection is the most useful projection for discovering A Fischer projection is the most useful projection for discovering

enantiomers. Compare the Glyceraldehyde enantiomer structures in enantiomers. Compare the Glyceraldehyde enantiomer structures in this diagram. this diagram.

D- and L-MonosaccharidesD- and L-Monosaccharides

CHO

H OH

CH2OH

CHO

CH2OH

HHO

D D

L-GlyceraldehydeD-Glyceraldehyde

[]25 = +13.5° []25 = -13.5°D-monosaccharideD-monosaccharide: a monosaccharide that, when written as a Fischer projection, has the -OH on its penultimate carbon on the rightL-monosaccharideL-monosaccharide: a monosaccharide that, when written as a Fischer projection, has the -OH on its penultimate carbon on the left


Properties of EnantiomersProperties of EnantiomersEnantiomers have, when present in a symmetric environment, identical chemical and physical properties

except for their ability to rotate plane-polarized light by equal amounts but in opposite directions. A mixture of equal parts of an optically active isomer and its enantiomer is termed racemic and has a net rotation of plane-polarized light of zero.Enantiomers of each other often do have different chemical properties related to other substances that are also enantiomers. Since many molecules in the bodies of living beings are enantiomers themselves, there is often a marked difference in the effects of two symmetrical enantiomers on living beings, including human beings.


What is Plane Polarized Light?What is Plane Polarized Light?


Optically active of enantiomersOptically active of enantiomers

CHO

H OH

CH2OH

CHO

CH2OH

HHO

D D


[]25 = +13.5° []25 = -13.5°


D- and L-MonosaccharidesD- and L-MonosaccharidesIn 1891, Emil Fischer made the arbitrary In 1891, Emil Fischer made the arbitrary

assignments of D- and L- to the enantiomers of assignments of D- and L- to the enantiomers of glyceraldehydeglyceraldehyde

CHO

H OH

CH2OH

CHO

CH2OH

HHO

D D


[]25 = +13.5° []25 = -13.5°


D- and L-MonosaccharidesD- and L-MonosaccharidesAccording to the conventions proposed by FischerAccording to the conventions proposed by Fischer

• D-monosaccharideD-monosaccharide: a monosaccharide that, when written as a Fischer projection, has the -OH on its penultimate carbon on the right

• L-monosaccharideL-monosaccharide: a monosaccharide that, when written as a Fischer projection, has the -OH on its penultimate carbon on the left


D- and L-MonosaccharidesD- and L-MonosaccharidesFollowing are Following are

• the two most common D-aldotetroses and • the two most common D-aldopentoses

D-Erythrose D-Threose D-Ribose 2-Deoxy-D-ribose

CH2OH

CHO

OH

OHH

H

CH2OH

CHO

OH

HHO

H

CH2OH

CHO

OH

OHH

H

CH2OH

CHO

OH

HH

H

OHH OHH


D- and L-MonosaccharidesD- and L-Monosaccharides• and the three common D-aldohexoses

CHO

H

OHH

HO

OHH

D-GlucosamineD-Glucose D-Galactose

CH2OH

OHH

CHO

H

OHH

HO

HHO

CH2OH

OHH

CHO

H

NH2H

HO

OHH

CH2OH

OHH


D- and L-MonosaccharidesD- and L-MonosaccharidesAmino sugarsAmino sugars

• N-acetyl-D-glucosamine is a component of many polysaccharides, including connective tissue such as cartilage; it is also a component of chitin, the hard shell-like exoskeleton of lobsters, crabs, and shrimp

CHO

OH

OH

H

NH2

H

H

HO

H

CH2OH

CHO

OH

OH

H

H

H

H

HO

H2N

CH2OH

CHO

OH

OH

H

NHCCH3

H

H

HO

H

CH2OH

OCHO

OH

H

H

NH2

H

HO

HO

H

CH2OH

4

2

D-Mannosamine(C-2 stereoisomer of D-glucosamine)

D-Glucosamine D-Galactosamine(C-4 stereoisomer of D-glucosamine)

N-Acetyl-D-glucosamine


Classification of MonosaccharidesMonosaccharides have the general formula CCnnHH2n2nOOnn

the most common have from 3 to 9 carbons

Triose (3) , tetrose(4), pentose(5), hexose(6)

• aldosealdose: a monosaccharide containing an aldehyde group: E.g. D-glucose

• ketoseketose: a monosaccharide containing a ketone group: E.g. D-Fructose


Carbohydrates: MonosaccharidesCarbohydrates: MonosaccharidesCarbohydrate:Carbohydrate: a polyhydroxy aldehyde, a polyhydroxy a polyhydroxy aldehyde, a polyhydroxy

ketone, or a polymeric substance that gives these ketone, or a polymeric substance that gives these compounds on hydrolysiscompounds on hydrolysis

Monosaccharide:Monosaccharide: a carbohydrate that cannot be hydrolyzed a carbohydrate that cannot be hydrolyzed to a simpler carbohydrateto a simpler carbohydrate

• monosaccharides have the general formula CCnnHH2n2nOOnn

• the most common have from 3 to 9 carbons• aldosealdose: a monosaccharide containing an aldehyde

group: E.g. D-glucose • ketoseketose: a monosaccharide containing a ketone group:

E.g. D-Fructose


MonosaccharidesMonosaccharides• monosaccharides are classified by their number of

carbon atoms

hexose

heptoseoctose

triosetetrosepentose

FormulaNameC3H6O3C4H8O4

C5H10 O5

C6H12 O6

C7H14 O7C8H16 O8


Aldoses: Trioses, Tetroses and PentosesAldoses: Trioses, Tetroses and Pentoses


Aldoses: HexosesAldoses: Hexoses


Ketoses: HexosesKetoses: Hexoses


MonosaccharidesMonosaccharides• there are only two trioses

• often aldo- and keto- are omitted and these compounds are referred to simply as trioses

• although this designation does not tell the nature of the carbonyl group, it at least tells the number of carbons

CHO

CHOH

CH2OH

CH2OH

C=O

CH2OH

Dihydroxyacetone (a ketotriose)

Glyceraldehyde (an aldotriose)


MonosaccharidesMonosaccharidesGlyceraldehyde contains a stereocenter and exists Glyceraldehyde contains a stereocenter and exists

as a pair of enantiomersas a pair of enantiomers

CHO

CH OH

CH2OH

CHO

C

CH2OH

HHO

(S)-Glycer-aldehyde

(R)-Glycer-aldehyde


Biochemically Important Monosaccharides


Cyclic Forms of Monosaccharides


Intramolecular cyclization• Simple sugars tend to exist primarily

in cyclic form through hemiacetal or hemiketal formation. It is the most

stable arrangement.

C

C

C

CH2OH

C

C

OH

O

H C

C

C

CH2OH

C

C

O

OH

aldehyde hemiacetal


Intramolecular cyclization

• The -OH group that forms can be above or below the ring resulting in two forms -

anomers anomers and and are used to identify the two are used to identify the two

formsforms..

- OH group is down compared to CH2OH (trans).

- OH group is up compared to CH2OH (cis).


Cyclization of D-glucose--DD - glucose - glucose

- - DD - glucose - glucose

H

OH

O H

OHOH

H

OHH

OH

CH 2 OH

H

C

C

C

C

C

CH 2 OH

OH

OH

H

OHH

HO

H

H

OH

OH

OH

OHOH

H

H

H

OH

CH 2 OH

H

OH


Haworth Projection Formulas


Haworth ProjectionsHaworth Projections• the anomers of D-glucopyranose

CHO

OH

H

OH

H

HO

H

H OH

CH2OH

HH OH

HHO

HOH

OH

H

CH2OHO

C

OH

HHO

HOH

H

CH2OHOH

O

H

OHH OH

HHO

HH

OH

H

CH2OHO

D-Glucose

-D-Glucopyranose (-D-Glucose)

()

()

-D-Glucopyranose (-D-Glucose)

anomeric carbon

+

anomericcarbon

5

5

1

1

redraw to show the -OH on carbon-5 close to thealdehyde on carbon-1

H


Haworth ProjectionsHaworth Projections• 5- and 6-membered hemiacetals are represented as

planar pentagons or hexagons viewed through the edge

• most commonly written with the anomeric carbon on the right and the hemiacetal oxygen to the back right

• -- means that -OH on the anomeric carbon is cis to the terminal -CH2OH; -- means it is trans

• a 6-membered hemiacetal is shown by the infix -pyranpyran- • a 5-membered hemiacetal is shown by the infix -furanfuran-

OOPyranFuran


Cyclic StructuresCyclic StructuresAldopentoses also form cyclic hemiacetalsAldopentoses also form cyclic hemiacetals

• the most prevalent forms of D-ribose and other pentoses in the biological world are furanoses

• the prefix deoxy- means “without oxygen”

OH ()

H

HOH OH

H HOHOCH2

H

OH ()

HOH H

H HOHOCH2

-D-Ribofuranose(-D-Ribose)

-2-Deoxy-D-ribofuranose(-2-Deoxy-D-ribose)


Cyclic StructuresCyclic StructuresD-Fructose, a 2-ketohexose, also forms a cyclic D-Fructose, a 2-ketohexose, also forms a cyclic

hemiacetalhemiacetal

O

HO

HOCH2H

HHO

CH2OH

OHH

OH

HO

HOCH2H

HHO

H

HHO

HOHOHOCH2

CH2OH

O

HCH2OH

OH5

5

1

2

2

()

-D-Fructofuranose(-D-Fructose)

-D-Fructofuranose(-D-Fructose)

()

1

anomericcarbon

5

1

2


Conformational FormulasConformational Formulas• five-membered rings are close to planar so that

Haworth projections are adequate to represent furanoses

O

OH()

H

HHO OH

H H


O

H

OH()

HHO OH

H H


HOCH2 HOCH2


Conformational FormulasConformational Formulas• the six-membered rings of pyranoses are more

accurately represented as chair conformations

OH

HO

H

HO

H

HOHH

OH

OH

OHH

HO

H

HO

H

HOHH

O

OH

OH

HO

H

HO

H

OHOHH

H

OH

OH

H

HO

H

HO

H

OOHH

H

OH

-D-Glucopyranose(-D-Glucose)[]D = +18.7°

-D-Glucopyranose(-D-Glucose)[]D = +112°

rotate aboutC-1 to C-2 bond


Conformational FormulasConformational Formulas• compare the orientations of groups on carbons 1-5 in

the Haworth and chair representations of -D-glucopyranose

• in each case, beginning at carbon 1, they are up-down-up-down-up

OCH2OH

HOHO

OHOH()H

H OH

HHO

HOH()

OH

H

CH2OHO

-D-Glucopyranose(chair conformation)

-D-Glucopyranose(Haworth projection)

123

4

5

6

1

23

4

5

6


MutarotationMutarotationMutarotation:Mutarotation: the change in specific rotation that the change in specific rotation that

occurs when the occurs when the or or forms of a carbohydrate forms of a carbohydrate are converted to an equilibrium mixture of the twoare converted to an equilibrium mixture of the two

+80.2

+80.2

+52.8

+150.7-D-galactose

-D-galactose

[] after Mutarotation

(degrees)[]

Monosaccharide% Present at Equilibrium

28

72

64

36-D-glucose

-D-glucose+112.0

+18.7

+52.7

+52.7

(degrees)


MutarotationMutarotationmutarotation of glucosemutarotation of glucose

[]D25 +18.7°

-D-Glucopyranose

-D-Glucopyranose

Open-chain form

()

()

[]D25 +112°

OHOH

HOHO

CH2OH

OCH2OH

O

HOHO

HOOH

OHO

C

CH2OHHO

HO

HO H


Fischer & Haworth ProjectionFischer & Haworth ProjectionIn solutions less than 1% of a sugar will be in the In solutions less than 1% of a sugar will be in the

linear form shown as Fischer projectionlinear form shown as Fischer projection

The normal form of most sugars is in a cyclic The normal form of most sugars is in a cyclic hemiacetal form shown as Haworth projectionhemiacetal form shown as Haworth projection


Converting Fischer to Haworth Converting Fischer to Haworth ProjectionProjection


-Cyclic form of Gulose


AldopentosesAldopentoses


Two monsaccharides connected by a bridging O atom called a glycosidic bond as

in sucrose.


Reactions of Monosaccharides


Disaccharides


Polysaccharides


Polysaccharides

• These are biopolymers composed of hundreds to thousands of simple sugar units (monosaccharides).

• The most common monosaccharide used

in polysaccharides is glucose.

C

C

C

C

C

CH 2 OH

OH

OH

H

OHH

HO

H

H

OH


Polysaccharides

• Uses for polysaccharidesUses for polysaccharides

• Storage polysaccharidesStorage polysaccharides

• Energy storage - starch and glycogen

• Structural polysaccharidesStructural polysaccharides

• Used to provide protective walls or lubricative coating to cells -

cellulose and mucopolysaccharides.

• Structural peptidoglycansStructural peptidoglycans

• Bacterial cell walls


Starch• Energy storage used by plants

• Long repeating chain of -D-glucose

• Chains up to 4000 units

• AmyloseAmylose straight chain

• AmylopectinAmylopectin branched structure

• Starch is a mixture of about 75% amylopectin and 25% amylose.


Amylose starch

• Straight chain that forms coils (1 4) linkage.

O

O

H

HOH

OH

CH2OH

OOH

OHH

HO

HOH2C

O OH

OH

H

HO

HOH2C

O

O

HOH

HHO

HOH2C

O

O

H

HO

H

OH

CH2OH

O

OH

OHH

OH

CH2OH

O

O

HHO

HOH

CH2OH


Amylose starch

Example showing coiled structure - 12 glucose units

- hydrogens and side chains are omitted.


Amylopectin starch• Amylopectin differs from amylose only in

that it has side chains. These are formed from

(1 6) links

• Side chains occur every 24-30 units.• Starch is stored as starch grains. They cannot diffuse from the cell and have little effect on the osmotic pressure of the cell.


Structural Polysaccharides


Glycogen• Energy storage of animals.

• Stored in liver and muscles as granules.

• Similar to amylopectin but more highly branched.

O

O

O

O

O

O

O

O

O

O

O

O

O

Oc

(1 6) linkageat crosslink

c


Cellulose

• Most abundant polysaccharide.

• (1 4) glycosidic linkages.

• Result in long fibers - for plant structure.

O O

H

OHH

OH

CH2OH

O OCH2OH

OHH

HO HO O

H

OHH

OH

CH2OH

O OCH2OH

OHH

HO HO O

H

OHH

OH

CH2OH

OCH2OH

OHH

HO H


H OO

HH

OHH

COO-

HO

H O

OH

O

HH

NH

CH2OH

H

C OCH3

H OO

HH

OHH

COO-

HO

H O

OH HH

NH

CH2OH

H

C OCH3

H OO

HH

OHH

COO-

HO

H O

OH

O

HH

NH

CH2OH

H

C OCH3O

Mucopolysaccharides• These materials provide a thin, viscous,

jelly-like coating to cells.

• The most abundant form ishyaluronic acid.

• Alternating units of• N-

acetylglucosamine • and D-glucuronic

acid.

(1 3)

(1 4)


Storage Polysaccharides


Acidic Polysaccharides


Glycolipids and Glycoproteins


Dietary Considerations and Carbohydrates


Cyclic StructureCyclic StructureMonosaccharides have hydroxyl and carbonyl Monosaccharides have hydroxyl and carbonyl

groups in the same molecule and exist almost groups in the same molecule and exist almost entirely as five- and six-membered cyclic entirely as five- and six-membered cyclic hemiacetalshemiacetals• anomeric carbonanomeric carbon: the hemiacetal carbon of a cyclic

form of a monosaccharide• anomersanomers: monosaccharides that differ in configuration

only at their anomeric carbons


GlycosidesGlycosidesGlycosideGlycoside: : a carbohydrate in which the -OH on its a carbohydrate in which the -OH on its

anomeric carbon is replaced by -ORanomeric carbon is replaced by -OR

HH OH

HHO

HOH

OH

H

CH2OHO

CH3OH H+

-H2O

OCH2OH

H

OH

OCH3H

HOH

OHH

H

OCH2OH

H

OH

HH

HOH

OHH

OCH3

(-D-Glucose)-D-Glucopyranose

Methyl -D-glucopyranoside(Methyl -D-glucoside)

anomeric carbon

+

+

Methyl -D-glucopyranoside(Methyl -D-glucoside)

glycosidicbond glycosidic

bond


GlycosidesGlycosidesGlycosidic bond:Glycosidic bond: the bond from the anomeric the bond from the anomeric

carbon of the glycoside to an -OR groupcarbon of the glycoside to an -OR group

To name a glycoside, name the alkyl or aryl group To name a glycoside, name the alkyl or aryl group bonded to oxygen followed by the name of the bonded to oxygen followed by the name of the carbohydrate; replace the ending carbohydrate; replace the ending -e-e by by -ide-ide• methyl -D-glucopyranoside• methyl -D-ribofuranoside


NN-Glycosides-Glycosides• the anomeric carbon of a cyclic hemiacetal also reacts

with an N-H of an amine to form an N-glycoside• especially important in the biological world are the N-

glycosides of D-Ribose and 2-deoxy-D-ribose with the following heterocyclic aromatic amines

HN

NH

O

O

Uracil

N

NH

O

NH2

Cytosine

HN

NH

O

O

Thymine

CH3N

N N

N

H

NH2

HN

N N

N

H

O

H2N

Adenine Guanine

Pyrimidine bases Purine bases


NN-Glycosides-Glycosides• following is the -N-glycoside formed between D-

ribofuranose and cytosine

H

H

H

H

OHOCH2

HO OH

NH2

O

N

N

anomericcarbon

a -N-glycosidicbond


Reduction to AlditolsReduction to AlditolsThe carbonyl group of a monosaccharide can be The carbonyl group of a monosaccharide can be

reduced to an hydroxyl group by a variety of reduced to an hydroxyl group by a variety of reducing agents, including NaBHreducing agents, including NaBH44

OHOH

HOHO

CH2OHO

CHOOHHHHOOHH

CH2OHOHH

NaBH4

CH2OHOHHHHOOHH

CH2OHOHH

D-Glucitol(D-Sorbitol)

D-Glucose-D-Glucopyranose


Reduction to AlditolsReduction to Alditols• name alditols by replacing the --oseose of the name of the

monosaccharide by -itol-itol• sorbitol is found in the plant world in many berries and

in cherries, plums, pears, apples, and seaweed; it is about 60% as sweet as sugar

• other common alditols include

CH2OH

CH2OH

OHHOHH

CH2OH

CH2OH

OHHHHOOHH

CH2OHHHOHHOOHH

CH2OHOHH

D-Mannitol XylitolErythritol


Oxidation to Aldonic AcidsOxidation to Aldonic AcidsThe -CHO group can be oxidized to -COOHThe -CHO group can be oxidized to -COOH

• reducing sugar:reducing sugar: any carbohydrate that reacts with an oxidizing agent to form an aldonic acid

oxidizingagent

D-GluconateD-Glucose

C

OHH

HHO

OHH

CH2OH

OHH

O HC

OHH

HHO

OHH

CH2OH

OHH

O O--D-Glucopyranose(-D-Glucose)

OCH2OH

HOHO

OHOH

basicsolution


Oxidation to Uronic AcidsOxidation to Uronic AcidsEnzyme-catalyzed oxidation of the 1° alcohol at Enzyme-catalyzed oxidation of the 1° alcohol at

carbon-6 of a hexose gives a uronic acidcarbon-6 of a hexose gives a uronic acid

CHO

CH2OH

OHHHHOOHHOHH

CHO

COOH

OHHHHOOHHOHH

HOHO

OHOH

COOHO

D-Glucose

enzyme-catalyzedoxidation

D-Glucuronic acid(a uronic acid)


Oxidation to Uronic AcidsOxidation to Uronic Acids• the body uses glucuronic acid to detoxify foreign

alcohols and phenols• these compounds are converted in the liver to

glycosides of glucuronic acid and then excreted in the urine

• the intravenous anesthetic propofol is converted to the following water-soluble glucuronide and excreted

O

OHOHO

OH

COO-

HO

Propofol A urine-soluble glucuronide


Glucose AssayGlucose AssayThe analytical procedure most often performed in The analytical procedure most often performed in

the clinical chemistry laboratory is the the clinical chemistry laboratory is the determination of glucose in blood, urine, or other determination of glucose in blood, urine, or other biological fluidbiological fluid• this need arises because of the high incidence of

diabetes in the population


Glucose AssayGlucose AssayThe glucose oxidase method is completely specific The glucose oxidase method is completely specific

for D-glucosefor D-glucose

+

+

glucoseoxidase

D-Gluconic acid

Hydrogen peroxide

-D-Glucopyranose

OHOH

HOHO

CH2 OHO

H2 O2

O2 + H2O

CO2H

CH2OH

OHHHHOOHHOHH


Glucose AssayGlucose Assay• O2 is reduced to hydrogen peroxide, H2O2

• the concentration of H2O2 is proportional to the concentration of glucose in the sample

• in one procedure, hydrogen peroxide is used to oxidize o-toluidine to a colored product, whose concentration is determined spectrophotometrically

NH2

CH3

H2O2peroxidase colored product+

2-Methylaniline(o-Toluidine)


Ascorbic Acid (Vitamin C)Ascorbic Acid (Vitamin C)L-Ascorbic acid (vitamin C) is synthesized both L-Ascorbic acid (vitamin C) is synthesized both

biochemically and industrially from D-glucosebiochemically and industrially from D-glucose

CHO

CH2OH

OHHHHOOHHOHH

CH2OH

OHH

HHO

O

OH

O

D-Glucose

both biochemialand industrial

syntheses

L-Ascorbic acid (Vitamin C)


Ascorbic Acid (Vitamin C)Ascorbic Acid (Vitamin C)• L-ascorbic acid is very easily oxidized to L-

dehydroascorbic acid • both compounds are physiologically active and are

found in most body fluids

CH2OH

OHH

HHO

O

OH

O

CH2OH

OHH

HO

O

O

O

L-Ascorbic acid (Vitamin C)

L-Dehydroascorbic acid

oxidation

reduction


SucroseSucroseTable sugar, obtained from the juice of sugar cane Table sugar, obtained from the juice of sugar cane

and sugar beetand sugar beet

O

HOOH

OH

CH2OH

O

HO

HOO

CH2OH

HOCH2

OHO

HO

O

OH

CH2OH

HO

HOO

CH2OH

HOCH2

1

1

2

1

2

1

-1,2-glycosidicbond

Sucrose

a unit of -D-glucopyranose

a unit of -D-fructofuranose


LactoseLactoseThe principle sugar present in milkThe principle sugar present in milk

• about 5 - 8% in human milk, 4 - 5% in cow’s milk

OHO

HOOH

O

CH2OH

O

HOOH

OH

CH2OH

OHO O

OH

OH

CH2OH

O OH

OH

OH

CH2OH

1

1

4 4

-1,4-glycosidic bond



MaltoseMaltoseFrom malt, the juice of sprouted barley and other From malt, the juice of sprouted barley and other

cereal grainscereal grains

OHO

HOOH

OOHO OH()

OH

CH2OH

CH2OHO

OH

O

OHHO

O OH()

HO

OH

CH2OH

HOCH2 14


1 4


Blood Group SubstancesBlood Group SubstancesMembranes of animal plasma cells have large Membranes of animal plasma cells have large

numbers of relatively small carbohydratesnumbers of relatively small carbohydrates• these membrane-bound carbohydrates are part of the

mechanism by which cell types recognize each other; they act as antigenic determinantsantigenic determinants

• among the first discovered of these antigenic determinants are the blood group substancesblood group substances

In the ABO system, individuals are classified In the ABO system, individuals are classified according to four blood types: A, B, AB, and Oaccording to four blood types: A, B, AB, and O• at the cellular level, the biochemical basis for this

classification is a group of relatively small membrane-bound carbohydrates


Blood Group SubstancesBlood Group Substances• one of these membrane-bound monosaccharides is L-

fucose

HHO

OHH

CH3

CHO

OHH

HHO

An L-monosaccharide;this -OH is on the left inthe Fischer projection

L-Fucose

Carbon 6 is -CH3 ratherrather than -CH2OH


Blood Group SubstancesBlood Group SubstancesA, B, AB, and O blood typesA, B, AB, and O blood types

N-Acetyl-D-galactosamine

D-Galactose N-Acetyl-D-glucosamine

D-Galactose N-Acetyl-D-glucosamine

Redblood cell

Type A

Type B

D-GalactoseType O N-Acetyl-D-glucosamine

Redblood cell

Redblood cell

D-galactose

(-1,4)

(-1,4)

(-1,3)

(-1,3)

(-1,3)

L-Fucose

(-1,2)

L-Fucose

(-1,2)

L-Fucose

(-1,2)


StarchStarchStarch is used for energy storage in plantsStarch is used for energy storage in plants

• it can be separated into two fractions; amylose and amylopectin

• amyloseamylose is composed of unbranched chains of up to 4000 D-glucose units joined by -1,4-glycosidic bonds

• amylopectinamylopectin is a highly branched polymer of D-glucose; chains consist of 24-30 units of D-glucose joined by -1,4-glycosidic bonds and branches created by -1,6-glycosidic bonds


StarchStarchFigure 18.4Figure 18.4


GlycogenGlycogenThe reserve carbohydrate for animalsThe reserve carbohydrate for animals

• a nonlinear polymer of D-glucose units joined by -1,4- and -1,6-glycosidic bonds

• the total amount of glycogen in the body of a well-nourished adult is about 350 g (about 3/4 of a pound) divided almost equally between liver and muscle


CelluloseCelluloseCellulose is a linear polymer of D-glucose units Cellulose is a linear polymer of D-glucose units

joined by joined by -1,4-glycosidic bonds-1,4-glycosidic bonds• it has an average molecular weight of 400,000,

corresponding to approximately 2800 D-glucose units per molecule

• both rayon and acetate rayon are made from chemically modified cellulose


CarbohydratesCarbohydrates

End Chapter 18End Chapter 18

18-1 Chemistry 121 Winter 2009 LA Tech Introduction to Organic Chemistry and Biochemistry Instructor...

Documents

Transcript of 18-1 Chemistry 121 Winter 2009 LA Tech Introduction to Organic Chemistry and Biochemistry Instructor...