Lecture 5 Carbohydrates TP

8/13/2019 Lecture 5 Carbohydrates TP

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Functions of sugars

Energy Source

D-glucose/glycogen/starch for metabolism

Structural Role

Cellulose in exoskeleton and cell walls, Hyaluronan and Pectin in extracellular matrix

Molecular RecognitionCovalently attached polymeric arrays of sugars form oilgosaccharides

Attached to side chain groups of proteins and others to lipids to form glycoproteins and glycolipids

Chemical code for identifying cells - variety of different sugars, the various ways in which they are linked,

variety of chemistry

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1

Aldehyde/ketone derivatives of

polyhydroxyalcohols

Aldehyde substitution - aldoses

Ketone substitution - ketoses

HCOH

CH2OH

HCOH

HCOH

CHO

HOCH

D-Glucose

D-Fructose

HCOH

CH2OH

HCOH

HOCH

C

CH2

OH

O

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Forms of simple sugars

C

CH

C

OH

HO H

C OHH

CH

CH2OH

OH

H OC

CHO

C

H

H OH

C HHO

CHO

CH2OHSugars are named as Dor L

according to the configuration

about this carbon atom, oneremoved from the terminal

position

D-Glucose (Glc)

showingnumbering

of atoms

1

2

3

4

5

6

L-Glucose

H

H O

D-Mannose (Man)

has the opposite

configuration at C-2

D-Galactose (Gal)

has the opposite

configuration at C-4

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O

OH

CH2OH

CH2OH

CH2OH

CH2OH

CH2OH

CH2OH

C H

C OH

OH

C

C

H

HO

H

H

1

2

3

4

5

6

OH H

H

H

H

HO

H OH

C

C

C C

H

HOH

H

HO

OH

C

H

O

C

OHO

OHH

D-Glucose

(linear form)

-D-Glucopyranose

(Haworth projection)

3

4

5

6

2

1

23

4

5

6

1

H

(a)

O

C H

C OH

OH

C

C

HO

H

H

1

2

3

4

5

6

C

C C

H

HOH2C

HOH2C

OH

C

O

OH H

D-Fructose

(linear form)

-D-Fructofuranose

(Haworth projection)

4

5

6

2

(b)

H

HO

3

1

O

H OH

OH

H

OH H

6

2

34

5

CH2OH1

Cyclization of sugars

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(4-1)

C

C

C

C

C

CH2OH

H O

H OH

H OH

H OH

HHO

O

OHOH

HOCH2OH

HHO

O

OHH

HOCH2OH

OHHO

DGlucose(free aldehyde form)

Pyranosering forms

(hemiacetalforms)

Cyclization of sugars produces more variety

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Types of simple aldose sugarsCHO

CH OH

CH2OH

CHO

CHO H

C

CHO

CH OH

CH OH

CH2OH

H OH

CH2OH

CHO

CHO H

CHO H

C

CHO

CH OH

CHO H

C OHH

CH2OH

H OH

CH2OH

CHO

CHO H

CH OH

C

CHO

CH OH

CH OH

C OHH

CH2OH

H OH

CH2OH

CHO

CH OH

CH OH

C OHH

CH OH

CH2OH

CHO

CHO H

CH OH

C OHH

CH OH

CH2OH

CHO

CH OH

CHO H

C OHH

CH OH

CH2OH

CHO

CHO H

CHO H

C OHH

CH OH

CH2OH

CHO

CH OH

CH OH

C HHO

CH OH

CH2OH

CHO

CHO H

CH OH

C HHO

CH OH

CH2OH

CHO

CH OH

CHO H

C HHO

CH OH

CH2OH

CHO

CHO H

CHO H

C HHO

CH OH

CH2OH

Galactose (Gal)

Arabinose (Ara)

Erythrose

Glyceraldehyde

Lyxose (Lyx)

Talose (Tal)

Threose

Mannose (Man)Glucose (Glc)

Ribose (Rib)

Gulose (Gul) Idose (Ido)Allose (All)Altrose (Alt)

Xylose (Xyl)

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CH2OH

C O

CH2OH

CH2OH

C O

CH OH

CH2OH

CH2OH

C O

CHO H

C OH

CH2OH

CH2OH

C O

CHO H

C HHO

CH OH

CH2OH

CH2OH

C O

CH OH

C OH

CH2OH

H

CH2OH

C O

CH OH

C HHO

CH OH

CH2OH

CH2OH

C O

CHO H

C OHH

CH OH

CH2OH

CH2OH

C O

CH OH

C OHH

CH OH

CH2OH

CH2OH

C O

CHO H

C OHH

CH OH

CH OH

CH2OH

Xylulose

Sorbose

Ribulose

Sedoheptulose

Fructose

Erythrulose

Dihydroxyacetone (not chiral)

TagatosePsicose

Types of simple aldose sugars

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Derivatives of simple sugars

O

OHOH

HO

CH2

HHO

HO

O

OHH

HO

CH2OH

OHHO

O

OHH

HO

H

OHHOH

O

NHH

HO

CH2OH

OHO

C

CH3

OOC

H CO

CH3

O

OH

OH

HN H

H

H COO

C

C

OHHHOH2C

HO

H

CH3C

O

O

OHH

HO

CH2OH

HHO

O

OHOH

HO

HO

SO3

4

1

6

Anion of muramic acid, O-Lactyl-GlcNAc (Mur),

2

1

-D-Glucose (Glc)of starch, glycogen

-D-Glucoseof cellulose

3

9

1,5-Anhydro-D-glucitol6-Sulfo--D-quinovose

Quinovose = 6-deoxy-D-glucose

Amylose (linear starch)contains only -1,4-glycosidiclinkages involving the groupsindicated by the arrows

Branched starches(amylopectin and glycogen)have branches added atthis position

found in bacterial cell wall polysaccharides.

Circled group is replaced by COO

inthe anion of -d-glucuronic acid (GlcA), acomponent of many mucopolysaccharides

This OH isreplaced by

in 2-acetamido-2-deoxy-d-glucose (N-acetylglucosamine

or GlcNAc), the monomer unit of chitin

N C

O

CH3

H

Anion of N-Acetylneuraminic acid (NeuAc),one of the Sialic acids (Sia), nine carbon

sugars found in many glycoproteins.

-D-Xylose of plant xylans

DFructofuranose (Fru)

CH2OH

OHHOH2C

HO

HO

O

1

2

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Diasaccharides

(4-6)

O

OH OH

HO

HOH2C

H

HO

O

OH OH

O

HOH2C

H

HO

O

OHHO

HOH2C H

HO

O

OH

HOH2C H

HO

H2O

-D-Glucopyranose (2 molecules)

1

OH

4

-1,4 Glycosidic linkage

O

Maltose, a disaccharide

H

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Types of diasaccharides

O

OH

OH

CH2OH

HOO

OHOH

CH2OH

HO

O

-Lactose

Note configuration

at this "reducingend" of the

molecule of-lactose

1 4

D-GlucoseD-Galactose

O

O

OHOH2C

HOCH2OH

OH

OH

HOCH2

HOHO

O

OOH

HOCH2

HO

HO

O

HO OH

OHCH2OH

Sucrose: Glcp12Fruf

, -Trehalose: Glcp11Glcp

1

2

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Conformations of Polysaccharides

l=0.42nm-1,4-Linked

D-Glucose units

H

41

H

O

O

OH

HO

OH

O

O

OH

HO

OH

O

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Cellulose

OO

CH2

OHO O

O

OOH O

O

CH2

OOH

OH

H

OCH2

OOH

H O

H

HOH

HO CH2H O

H

A

Hydrogen

Oxygen

Carbon

!(1,4) linked glucose units

Unbranched polymer

Most abundant polysaccharide

",#angles are constrained

Individual glucose units are arranged

at 180 from each other

H-bonding within and across polymers

confers stability

2 closely arranged parallel chains

form stacks which organize into fibres

Each fibre is ~3.5-4.0 nm long with

30-40 parallel chains each containing

2000-10,000 glucose units to form

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Starch $(1,4) and $(1,6) linked glucose units

Branched polymer

Most abundant polysaccharide

Growth occurs at the non-reducing

ends

Reducing end may be attached to

proteins

Shows a broom-like arrangement

Amylopectin molecules are 120-400

nm long and have a molecular mass of

15-30 MDa

Amylose have molecular masses of

100 KDa

Intrinsic bend around the glycosidic

linkage leads to formation of helices, 6

residues per turn, 0.8 nm pitch anddiameter of 14 nm

O

OH

CH2

HO

OH

O

O

H2C

O

O

HO

OH

OH

O

H2C

HOO

HO

O

OHOH

CH2

HOO

O

The linear chains of amylase growfrom the reducing end towardthe non-reducing end using only1,4 linkages as in maltose.

For each residue the chainbends by ~60leading toa helical structure with 6residues per turn.

Branches inamylopectin orglycogen areattached by1,6 linkages.

~60

~60

A

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Polysaccharides

Starch Green plants

Amylose D-Glucose 1,4

Amylopectin D-Glucose 1,4 1,6Glycogen Animals, bacteria D-Glucose 1,4 1,6

Cellulose Green plants, some bacteria D-Glucose 1,4

Dextrans Some bacteria D-Glucose 1,6 1,3

Pullulan Yeast D-Glucose 1,6 + 1,4

Callose Green plants D-Glucose 1,3

Yeast glucan Yeast D-Glucose 1,3

Schizophyllan, curdlan, paramylon D-Glucose 1,3 1,6 on every third residue

Mannans Algae D-Mannose 1,4

Yeast D-Mannose 1,6

Xylans Green plants D-Xylose 1,3

Brown seaweed

Inulin Some plant tubers D-Fructose 2,6

Chitin Fungi, anthropods N-acetyl-D-Glucosamine 1,4

Alternating polysaccharides

Hyaluronan Animal connective tissue Glucuronic acid +

N-acetylglucosamine 1,4

Chondroitin sulfate D-Glucosamine

N-acetyl-D-Galactosamine 1,3 + 1,4

Dermatan sulfate -L-Iduronate +

N-acetyl-D-Galactosamine 1,3 + 1,4

Pectin Higher plants D-Galactunonate + others 1,4 + others

Alginate Seaweed D-Mannuronate +

L-Guluronate 1,4 + 1,4

Agar-agar Red seaweed Galactose 1,4 and 1,3

Carageenan Red seaweed Galactose-4-sulfate + 1,4 + 1,3

3,6-anhydro-

D-Galactose-2-sulfate

Murein Bacterial cell wall N-acetyl-D- 1,4

Glucosamine + N-

Name Source Monomer Main linkage Branch linkages

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Glycoproteins and proteoglycans

Common to proteins displayed at the cell surface and secreted proteins

O-linked glycosides to side chains of serine/threonine and N-linked to

asparagine side chain but variations exist

Xyl1O-Ser(Thr) Proteoglycans of connective tissue;thyroglobulins

NLys Some dermatan sulfates

H

Gal1O-Hydroxylysine Collagen, extension (Hydroxyproline)

L-Ara1O-4-Hydroxy-proline Plants

GalNAc1O-Ser(Thr) Many glycoproteins

GlcNAc1O-Ser(Thr) Glycoproteins of cytoplasmic

surfaces

GlcNAc1NH-CH2-Asn Many glycoproteins

Some dermatan and heparan sulfates

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O-linked glycosaminoglycans

Repeating unit ofchondroitin as in Fig. 4-11 Terminal unit

3Gal1

3Gal1

4Xyl1O-Ser

(4GlcA13GalNA1)n4GlcA1

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N-linked glycosaminoglycans

O

N

HOCH2

N

O

HO

R

HC

CH3

OH

CH2 C

O

Amide N of

asparagine

Man14GlcNA14GlcNA1Asn

Fuc1

63

Y112Man1

Y213Man1

6

Y31

6

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Tutorial topics

BOX 4-A CYCLODEXTRINS

BOX 4-C THE BLOOD GROUP DETERMINANTS

BOX 4-D ANTIFREEZE AND ICE-NUCLEATION PROTEINS

Lecture 5 Carbohydrates TP

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