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Sugars and Polysaccharides. An Introduction W.T. Winter [email protected] 215 Jahn Lab; x6876. Overview. Monosaccharides? Oligosaccharides? Polysaccharides Glycoproteins and Proteoglycans. Carbohydrates Are Chiral Molecules. Typically but not always L – amino acids D - sugars. D.

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An introduction w t winter wtwinter@syr edu 215 jahn lab x6876

Sugars and Polysaccharides

An Introduction

W.T. Winter

[email protected]

215 Jahn Lab; x6876


Overview
Overview

  • Monosaccharides?

  • Oligosaccharides?

  • Polysaccharides

  • Glycoproteins and Proteoglycans


Carbohydrates are chiral molecules
Carbohydrates Are Chiral Molecules

  • Typically but not always

  • L – amino acids

  • D - sugars

D

Hence, these molecules have a measurable optical rotation, which depends upon both the monomer residues and their conformation

L

Glyceraldehyde


Fisher Formulas

Next to last carbon determines D or L

New carbon is added as C1


A way to explore monosaccharides
A Way to Explore Monosaccharides

  • John Maser at Leeds has developed a “Monosaccharide Browser” the site is

    http://www.beechtreecommon.org/biochemistry/monosaccharide/





B d glucose
b-D-Glucose

a and b are “anomers and differ in configuration at the new chiral center formed in the cycle

  • In nature, open chain forms are rare.

  • NMR has shown that all 5 coexist with the pyranose forms occurring 99% of the time, furanose about 0.5% each and a trace of open chain


Pyranose ring shapes
Pyranose Ring Shapes

Pyranose rings can form chair and boat

conformers

1C44C1


Sucrose
Sucrose

  • 1-2 linked alpha glucose, beta fructose

  • Sources sugar cane

    sugar beet


Polysaccharides
Polysaccharides

  • Polysaccharides consist of sugar residues linked into a polymer.

  • Polysaccharides, unlike proteins or nucleic acids, are not always linear in sequence

  • The most abundant biomolecules in nature-about 1012 tons of cellulose are synthesized each year

  • Functions: structural, food storage, cell surfaces, extracellular matrices.


Polysaccharides may be the most diverse biomolecules
Polysaccharides May Be the Most Diverse Biomolecules

From one 6 carbon hexopyranose sugar such as glucose, you can make 11 different disaccharides and 8 of those lead to infinite polymers

From one amino acid or nucleotide you can make only a single dimer.

-D-Glucose-D-Glucose


Cellulose structural polysaccharide from glucose
Cellulose: Structural polysaccharide from glucose

n ~ 5000-10000

Also found in some bacteria, algae, fungi, seed hairs, and animals (tunicates or sea squirts)

Microfibrils

of cellulose

Wood cell (fiber) cell walls are made of cellulose + lignin and hemicelluloses


Starch a d glucose polymer found as an energy storage material in foods
Starch: a-D-Glucose polymer found as an energy storage material in foods

Unlike cellulose, starch can be metabolized by humans. Starches provide the bulk of the energy we obtain from grains, potatoes etc.

Amylose

Amylopectin


Extracellular matrix hyaluronic acid
Extracellular Matrix: Hyaluronic acid material in foods

A regular copolymer of N-acetyl glucosamine and Glucuronic Acid (as a metal salt)


Ha cont
HA cont material in foods

Found in:

  • synovial fluid (knee, shoulder )

  • Vitreous humor (eye- used in reconstructive eye surgery)

  • Skin – small amounts in all connective tissues



Other structural polysaccharides
Other Structural Polysaccharides proteoglcans

  • Mannans – some algae

  • Alginic acids – many algae

  • Chitin- insects, crustaceans (shrimp shell), fungi.


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