26 c!#$%&’!()*...26.4 isomerizations of monosaccharides epimers figure 26.4 isomerization of...

C!"#$%&'"!()*26

SUCROSE

26.3 CHIRALITY OF MONOSACCHARIDES

CHO

C OHH

CH2OH

(R)-glyceraldehyde[!]D = + 13.5o

CHO

OHH

CH2OH

Fischer projection25

CH2OH

C O

C HHO

C

C

OHH

CH2OH

OHH

D-fructose

CH2OH

O

HHO

OHH

CH2OH

OHH

Fischer projection

CHO

C OH

C HHO

C

C

HHO

CH2OH

OHH

D-galactose

Fischer projection

H

CHO

OH

HHO

HHO

CH2OH

OHH

H

carbonyl group at top carbonyl near top

26.3 CHIRALITY OF MONOSACCHARIDESAldoses

CHO

(CH2OH)n

C OHH

CH2OH

a D aldose

CHO

(CH2OH)n

C HHO

CH2OH

an L aldose

CHO

HHO

CH2OH

CHO

OHH

CH2OH

mirror plane

D-ribose

CH2OH

C O

C HHO

C

C

OHH

CH2OH

OHH

D-fructose

CHO

C OHH

C OHH

CH2OH

D-glyceraldehyde D-glucose

CHO

C OH

C HHO

C

C

OHH

CH2OH

OHH

HCHO

C OHH

C

C

OHH

CH2OH

OHH


D-allose

CHO

OH

OHH

OHH

CH2OH

OHH

H

D-altrose

CHO

H

OHH

OHH

CH2OH

OHH

HO

D-glucose

CHO

OH

HHO

OHH

CH2OH

OHH

H

D-mannose

CHO

H

HHO

OHH

CH2OH

OHH

HO

Aldohexoses

D-gulose

CHO

OH

OHH

HHO

CH2OH

OHH

H

D-idose

CHO

H

OHH

HHO

CH2OH

OHH

HO

D-galactose

CHO

OH

HHO

HHO

CH2OH

OHH

H

D-talose

CHO

H

HHO

OHHO

CH2OH

OHH

HO

D-erythrose

CHO

C OHH

CH2OHD-glyceraldehyde

CHO

OHH

CH2OH

OHH

Aldotriose

D-arabinose

CHO

HHO

OHH

CH2OH

OHH

D-lyxose

CHO

HHO

HHO

CH2OH

OHH

D-threose

CHO

HHO

CH2OH

OHHAldotetroses

D-ribose

CHO

OHH

OHH

CH2OH

OHH

D-xylose

CHO

OHH

HHO

CH2OH

OHH

Aldopentoses

Figure 26.1 Structures of D-Aldoses


Figure 26.2 Enantiomeric Relationship of D- and L-Monosaccharides!e D- and L-monosaccharides have reversed, mirror image configurations at every chiral center.

mirror

D-glucose

CHO

OH

HHO

OHH

CH2OH

OHH

H

Determines D configuration

D-gluco configuration

D-glucose

CHO

H

OHH

HHO

CH2OH

HHO

HO

Determines L configuration

L-gluco configuration

26.3 CHIRALITY OF MONOSACCHARIDESKetoses

D-erythulose

CH2OH

C O

CH2OHdihydroxyacetone

CH2OH

C

C

O

CH2OH

OHH

Ketotriose

Ketotetrose

D-ribulose

CH2OH

C O

C

C

OHH

CH2OH

OHH

D-xylulose

Ketopentoses

CH2OH

C O

C

C

HHO

CH2OH

OHH

D-sorbose D-psicose D-fructose

CH2OH

C O

C HHO

C

C

HHO

CH2OH

OHH

D-tagatose

CH2OH

C O

C OHH

C

C

HHO

CH2OH

OHH

CH2OH

C O

C OHH

C

C

OHH

CH2OH

OHH

CH2OH

C O

C HHO

C

C

OHH

CH2OH

OHH

Ketohexoses

Figure 26.3 Structures of D-2-Ketoses

26.3 CHIRALITY OF MONOSACCHARIDESLess Common Monosaccharides

D-apiose

CHO

OHH

CH2OH

OHHOCH2

(a 3-ketopentose)

CH2OH

C OH

C

C

O

CH2OH

OHH

H

2-deoxy-D-ribose

CHO

C HH

C

C

OHH

CH2OH

OHH

D-2-glucosamine

CHO

C NH2

C HHO

C

C

OHH

CH2OH

OHH

H

N-acetyl-D-2-glucosamine

CHO

C NH

C HHO

C

C

OHH

CH2OH

OHH

H C CH3

O

26.4 ISOMERIZATIONS OF MONOSACCHARIDESEpimers

D-galactose

CHO

OH

HHO

HHO

CH2OH

OHH

H

D-glucose

CHO

OH

HHO

OHH

CH2OH

OHH

H

D-mannose

CHO

H

HHO

HHO

CH2OH

OHH

HO

C-4 epimers

C-2 epimers

1 11

22 2

333

4 4 4

5 5 5

6 6 6

CHO

C OHH

R

CHO

C HHO

Repimer 1 epimer 2

C

COHH

R OH

enediol(E and Z)

26.4 ISOMERIZATIONS OF MONOSACCHARIDESEpimers

Figure 26.4 Isomerization of Aldoses via an Enediol Intermediate

enediolD-glucose

CHO

OH

HHO

OHH

CH2OH

OHH

H

D-mannose

C

HHO

HHO

CH2OH

OHH

C OHH

OHCHO

H

HHO

OHH

CH2OH

OHH

HO

not chiral

26.4 ISOMERIZATIONS OF MONOSACCHARIDESInterconversion of Aldoses and Ketoses

CHO

C OHH

R

CH2OH

C O

R(an aldolse) (a ketose)

C

COHH

R OH

(an enediol)

D-fructose-6-phosphate

CH2OH

O

HHO

OHH

CH2OPO32-

OHH

D-glucose-6-phosphate

CHO

OH

HHO

OHH

CH2OPO32-

OHH

Hglucose-6-phosphateisomerase

26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALS

O

H

HO

H

HO

H

OHOHH

H

OH

OH

H

HO

OH

H

OH

HHH

O

OH

D-glucose !-D-glucopyranose

+O

H

HO

OH

H

OH

HHH

OH

OH

"-D-glucopyranose

OO

furan pyran

COHO

H

CO

HH

O

5-hydroxypentanal

or

O

OH

H

K = 20CO

H

OHCO

HH

O


C-1 CHO group

C-5 hydroxyl group

C-1

C-5 hydroxyl groupbond formation gives hemiacetal

rotation around C-3 C-4 ! bond

D-glucose

C-1 axial OH

!-D-glucopyranose "-D-glucopyranose

C-1 equatorial OH


!-D-fructofuranose

OH

CH2OH

H

HOH2C

H OH

HO HO

D-fructose

CH2OH

H

HOH2C

H OH

HO HOH

O+

"-D-fructofuranose

CH2OH

OH

H

HOH2C

H OH

HO HO

Table 26.1Composition of Monosaccharides at Equilibrium in Solution (in percent)Monosaccharide Pyranose Furanose

! " ! "D-glucose 36 64D-mannose 67 32 0.8 0.2D-galactose 31 69D-allose 18 70 5 7D-altrose 27 40 20 13D-idose 38 38 10 14D-talose 40 29 20 11D-arabinose 63 34 2 1D-ribose 20 56 6 18D-xylose 27 63D-fructose 2 66 7 25


26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALSHaworth Projection Formulas

Figure 26.5 Haworth Projections of a Pyranose and a Furanose

OH

HOOH

H

CH2OH

HOH

HH

OH

Haworth projection of !-D-glucopyranose

OHOH2C

HH

OH

HO

H

CH2OH

OH

Haworth projection of "-D-fructofuranose

The C-6 CH2OH group is "up" in a Haworth projection of a D-pyranose or D-furanose.

The "-hydroxy group at C-1 is"down" in a Haworth projection of an "-D-pyranose or furanose. It is "up" in the ! anomer.

26.5 CYCLIC MONOSACCHARIDES: HEMIACETALS AND HEMIKETALSMutarotation

O

H

HO

H

HO

H

OHOHH

H

OH

OH

H

HO

OH

H

OH

HHH

O

OH

D-glucose!-D-glucopyranose

crystalize frommethanol

!-D-glucopyranosemp 146o

[!]D = + 112.2o

O

H

HO

OH

H

OH

HHH

OH

OH

"-D-glucopyranose

crystalize fromacetic acid

"-D-glucopyranosemp 150o

[!]D = + 18.7o

26.6 REDUCTION AND OXIDATION OF MONOSACCHARIDESReduction of Monosaccharides

D-glucitol (D-sorbitol) (an alditol)

CH2OH

C OH

C HHO

C

C

OHH

CH2OH

OHH

H

reduced

O

H

HO

H

HO

H

OHOHH

H

OHOH

H

HO

OH

H

OH

HH

OH


NaBH4

C

H

O

OHH

HO

OH

H

OH

HH

OH

D-glucitol

COH

HH

26.6 REDUCTION AND OXIDATION OF MONOSACCHARIDESOxidation of Monosaccharides

D-gluconic acid(an aldonic acid)

CO2H

C OH

C HHO

C

C

OHH

CH2OH

OHH

H

oxidized

O

H

HO

H

HO

H

OHOHH

H

OHOH

H

HO

OH

H

OH

HH

OH


[O]

C

H

O

OHH

HO

OH

H

OH

HH

OH

D-gluconic acid

C

OH

O


D-glucaric acid(an aldaric acid)

CO2H

C OH

C HHO

C

C

OHH

CO2H

OHH

H

oxidized

oxidized

O

H

HO

H

HO

H

OHOHH

H

OHOH

H

HO

OH

H

OH

HH

OH


[O]

C

H

O

1o alcohol

OHH

HO

OH

H

OH

HH

C

D-glucaric acid

C

OH

O

OHO


O

H

HO

H

HO

H

OHOHH

H

OH

!-D-glucopyranose

NADP+-dependentdehydrogenase

1o alcohol

O

H

HO

H

HO

H

OHOHH

H

CO2H

D-glucuronic acid

26.7 GLYCOSIDES

OH

C OR'R

H(a hemiacetal)

+ R'OHH+

OR'

C OR'R

H

+ OHH

(an acetal)

OH

C OR'R

H(a hemiketal)

+ R'OHH+

OR'

C OR'R

H

+ OHH

(a ketal)

O

H

HO

H

HO

H

HOHH

OCH3

OH

methyl !-D-glucopyranoside

!-glycosidic bond

aglycone

26.7 GLYCOSIDES

O

H

HO

H

HO

H

HOHH

OH

O

H

HO

H

HO

H

HOHH

OH

resonance-stabilized oxocarbocation intermediate

O

H

HO

H

HO

H

HOHH

OH

OH

!-D-glucose

H+O

H

HO

H

HO

H

HOHH

O

OH

H

H

O

H

HO

H

HO

H

HOHH

OH

-HOH

26.7 GLYCOSIDESFigure 26.7 Formation of ! and " Glysosides

O

H

HO

H

HO

H

HOHH

OH

CH3OH

O

H

HO

H

HO

HH

OHH

OH

OCH3

H

-H+

O

H

HO

H

HO

HH

OHH

OH

OCH3

methyl !-D-glycopyranoside

HOCH3

O

H

HO

H

HO

HOCH3

OHH

OH

H

H

O

H

HO

H

HO

HOCH3

OHH

OH

Hmethyl "-D-glycopyranoside

-H+

26.8 DISACCHARIDESMaltose

O

H

HO

H

HO

H

OHH

OH

O

H

O

H

H

HOH

OHH

OH

H

OH!-(1,4') glycosidic bond

4-O-(!-D-glucopyranosyl)-"-D-glucopyranose (maltose)

"-anomer of glucose,the agylcone.

26.8 DISACCHARIDESMaltose

Figure 26.8 Molecular Model of Maltose.!e monosaccharide unit on the left is the hemiacetal of the !-D-glucopyranosyl unit. It is linked by an !-(1,4’) glycosidic bond to "-D-glucopyranose, the aglycone. !e oxygen atom of the glycosidic bond is approximately in the center of the structure, between the two rings. It is projected down, axial, and therefore !. It is linked to C-4 of the aglycone, and so the link is axial-equatorial.

4-O-(!-D-glucopyranosyl)-"-D-glucopyranose (maltose)

"-D-glucopyranose unit,the aglycone

"-equatorial hydroxyl group

!-D-glucopyranosylunit

!-axial oxygen of (1,4’)-gycosidic bond

26.8 DISACCHARIDESCellobiose

O

H

HO

H

HO

H

OHH

OH

H

O

!-(1,4') glycosidic bond

4-O-(!-D-glucopyranosyl)-!-D-glucopyranose (cellobiose)

O

H

HHO

H

HOH

OH

HOH

!-anomer of glucose,the agylcone.

!-D-glucopyranosyl unit

26.8 DISACCHARIDESCellobiose

Figure 26.9 Molecular Model of Cellobiose!e monosaccharide unit on the left is the !-D-glucopyranosyl portion of cellobiose. It is linked by a !-(1,4’) glycosidic bond to !-D-glucopyranose, the aglycone. !e oxygen atom of the glycosidic bond is approximately in the center of the structure, between the two rings. It is projected up, equa-torial, and therefore it is !. It is linked to C-4 of the aglycone, and so the link is equatorial-equatorial.



!-D-glucopyranoseunit, the aglycone

!-equatorial hydroxyl group

!-glycosidic bond

1 4’

26.8 DISACCHARIDESLactose

O

H

HO

H

HO

H

OHH

OH

H

O



O

H

HHO

H

HOH

OH

HOH


!-D-glucopyranosyl unit


O

HO

H

H

HO

H

OHH

OH

H

O


4-O-(!-D-galactopyranosyl)-!-D-glucopyranose (lactose)

O

H

HHO

H

HOH

OH

HOH


!-D-galactopyranosyl unit

C-4 epimer of glucose


Figure 26.10 Molecular Model of Lactose!e monosaccharide unit on the left is the !-D-galactopyranosyl portion of cellobiose. It is linked by a !-(1,4’) glycosidic bond to !-D-glucopyranose, the aglycone. Galactose is the C-4 epimer of glucose. !us, the hydroxyl group at C-4, which is equatorial in glucose, is axial in galactose.

4-O-(!-D-galactopyranosyl)-!-D-glucopyranose (lactose)

!-D-galactopyranosylunit

!-D-glucopyranoseunit, the aglycone

!-equatorial hydroxyl group

!-glycosidic bond

C-4 epimer of glucose, axialhydroxyl group

1 4’

26.8 DISACCHARIDESSucrose

O

H

HO

H

HO

H

OHH

OH

O

H

!-anomer of glucose

!-D-glucopyranosyl-"-D-fructofuranoside (sucrose)

"-anomer of fructose

CH2OHH

HOH2C

H OH

HO HO

(1,2')-glycosidic bond

Figure 26.11 Molecular Model of Sucrose!e monosaccharide unit on the left is the !-D-galactopyranosyl portion of sucrose. It is linked by a (1,2’) glycosidic bond to "-D-fructofuranose. !us, the anomeric carbons of the monomers are linked by a glycosidic bond. Sucrose is an acetal. !erefore, it is a nonreducing sugar.

26.8 DISACCHARIDESSucrose

!-D-glucopyranosyl-"-D-fructofuranoside (sucrose)


"-D-fructofuranoseunit

"

!1

2’

26.9 POLYSACCHARIDES

O

HO

HO

HO

O O

HO

HO

HO

O O

HO

HO

HO

O O

HO

HO

HO

O

!-(1,4')-glycosidic bonds

cellulose

O

HO

HO

HOO

O

O

O

OO

O

HOHO

HOHO

HOHO

OH

OH

OH

amylose

"-(1,4')-glycosidic bonds

O

HO

HO

HOO

O

O

O

OO

O

HOHO

HOHO

HOHO

OH

O

OH

amylopectin (or glycogen)

"-(1,4')-glycosidic bonds

O

HO

HO

"-(1,6')-glycosidic bonds at branch points

Figure 26.12 Structures of Polysaccharides

26.9 POLYSACCHARIDES

Trisaccharide segment of amylose

!-(1,4’)-glycosidic bonds4’

!-D-glucopyranosyl groups

4’ 4’

1

1

1! !

Figure 26.13 Three !-D-Glucopyranosyl Groups in AmyloseWhen we say that a polymer is “linear” we mean that the polymer contains no branches. Amylose coils into a helix.

26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESPeriodate Oxidation

vicinal diol in monosaccharide

C

C

OHH

OHH

HIO4 C

C

OH

OH+

aldehyde or ketone

aldehyde or ketone

vicinal diol at 1o alcohol

R

C

C

OHH

H

OHH

HIO4

R

C

C

OH

H

OH+

an aldehyde

formaldehyde

26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESPeriodate Oxidation

(an aldose)

OC

C

H

R

OHH

HIO4

OH

C

C

OH

R

OH+

formic acid

(an aldehyde)+ H2O

OH

C

C

OHH

OHH

(a ketose)

CH2OH

C

C

O

R

OHH

HIO4 CH2 Oformaldehyde

+ H2O

CH2OH

C

C

OHHO

R

OHH

OC

C

OH

R

OHH +

(a carboxylic acid)

HC

R

OHIO4

OC

C

OH

R

OHH + O C O

26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESOxidation and Optical Activity

D-galactose

CHO

OH

HHO

HHO

CH2OH

OHH

H

HNO3

CO2H

OH

HHO

HHO

CO2H

OHH

H

optically inactive aldaric acid

plane of symmetry

26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESFormation of Osazones

CHO

C

(CH2OH)n

CH2OH

(an aldose)

OHH NH2NHC6H5

CH

C

(CH2OH)n

CH2OH

NHNHC6H5

NHNHC6H5

(an osazone)

CH2OH

C

(CH2OH)n

CH2OH

(a ketose)

O NH2NHC6H5

CH

C

(CH2OH)n

CH2OH

NHNHC6H5

NHNHC6H5

(an osazone)

26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESChain Extension of Aldoses

D-ribose

CHO

OHH

OHH

CH2OH

OHH

D-allose

CHO

OH

OHH

OHH

CH2OH

OHH

H

D-altrose

CHO

H

OHH

OHH

CH2OH

OHH

HO

+

oxidation

D-aldaric acid(optically inactive)

CO2H

OH

OHH

OHH

CO2H

OHH

H

(+)-D-altraric acid

CO2H

H

OHH

OHH

CO2H

OHH

HO

oxidation

26.10 CHEMICAL DETERMINATION OF MONOSACCHARIDE STRUCTURESChain Shortening of Aldoses

(one diastereomer)

CHO

C

C

OHH

R

OHH

NH2OH

CH

C

C

OHH

R

OHH

NOH

(an oxime)

Ac2O

C

C

C

OAcH

R

OAcH

N

C

C

C

OAcH

R

OAcH

N

CH3O

C

C

C

OHH

R

OHH

N

CH3O C

C

OH

R

OHH+ CH3OH+CN

26.11 DETERMINATION OF RING SIZE

OCH3H

CH2OH

H OH

OH HO

methyl !-D-ribofuranoside

HO

H

HO

OH

H

H

OHOCH3

H

methyl !-D-ribopyranoside

OCH3H

CH2OH

H OH

OH HO

methyl !-D-ribofuranoside

HIO4

- OC C

HOCH2

H CHO CHO

HOCH3

dialdehyde product

O

H

HO

OH

H

H

OHOCH3

H

methyl !-D-ribopyranoside

IO4-

O

dialdehyde product

+ HCO2HC H

C OCH3

OH

O

H

O

H

HO

H

HO

H

OHH

OH

OH

H

!-D-glucopyranose

(CH3)2SO4O

H

CH3O

H

CH3O

H

OCH3H

OCH3

OCH3

H

methyl 2,3,4,6-tetra-O-methyl-!-D-glucopyranoside

O

H

CH3O

H

CH3O

H

OCH3H

OCH3

OH

H

2,3,4,6-tetra-O-methyl-!-D-glucopyranose

H3O+



2,3,4,6-tetra-O-methyl-D-glucose

CHO

C OCH3

C HCH3O

C

C

OCH3H

CH2OCH3

OHH

H

oxidation

CO2H

C OCH3

C HCH3O

C

CO2H

OCH3H

H

dicarboxylic acid product

26.12 CHEMICAL DETERMINATION OF DISACCHARIDE STRUCTURE

OO

OHOCH2

HOOH

OH

HO

HO

OHHOCH2

(CH3)2SO4

lactose

OO

OCH3OCH2

OOCH3

OCH3

CH3O

CH3O

OCH3

CH3OCH2

octamethyllactose

CH3

OO

OCH3OCH2

OOCH3

OCH3

CH3O

CH3O

OCH3

CH3OCH2

CH3

H3O+ OOH

OCH3

CH3O

OCH3

CH2OCH3

+O

OH

OCH3

CH3O

CH2OCH3

HO

2,3,4,6-tetra-O-methyl-D-galactose 2,3,6-tri-O-methyl-D-glucoseoctamethyllactose

26.13 HUMAN BLOOD GROUP ANTIGENS

O

OH

H

OH

H

H

NHOH

H

N-acetylgalactosamine (GalNAc)

CCH3O

O

H

HO

OH

H

H

NHOH

H

N-acetylglucosamine (GlcNAc)

CCH3O

OH OH

O

H

CH3

OH

H

H

OHH

OH

6-deoxy-a-L-galactose (a-L-fucose)

OH

H


OO

O

O

HO

OH

!-GalNAcOH

OHOH

OO

HO

HOCH2

NHC

CH3

O

!-GlcNAc

Gal

NHC

O

CH3OCH3

OHOH

OH

"-L-fucose

Type A

Oprotein

OO

O

O

HO

OH

GalOH

OHOH

OO

HO

HOCH2

NHC

CH3

O

!-GlcNAc

Gal

HO

OCH3

OHOH

OH

"-L-fucose

Type B

Oprotein

HOO

O

OHOH

OO

HO

HOCH2

NHC

CH3

O

!-GlcNAc

galactose

OCH3

OHOH

OH

"-L-fucose

Type O

Oprotein


Type O Blood Group Antigen

!-D-galactopyranosyl

"-L-fucopyranosyl!-GlcNAc group

1

2’

1

"-(1,2’)-glycosidic bond

!-(1,4’)-glycosidic bond

1

6

6

6

2

4’

"

!

26 c!#$%&’!()*...26.4 isomerizations of monosaccharides epimers figure 26.4 isomerization of...

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