An introduction w t winter wtwinter@syr edu 215 jahn lab x6876
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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 [email protected] 215 Jahn Lab; x6876

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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


An introduction w t winter wtwintersyr 215 jahn lab x6876

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/


Epimers differ by configuration at one chiral center

Epimers Differ by Configuration at One Chiral Center


Sugars prefer to be cyclic

Sugars Prefer To Be Cyclic


Hemiacetals and cyclization group

Hemiacetals and Cyclization Group


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

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


Ha cont

HA cont

Found in:

  • synovial fluid (knee, shoulder )

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

  • Skin – small amounts in all connective tissues


Connective tissues fibrous proteins polysaccharides and proteoglcans

Connective Tissues- fibrous proteins, polysaccharides, and proteoglcans


Other structural polysaccharides

Other Structural Polysaccharides

  • Mannans – some algae

  • Alginic acids – many algae

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


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