An introduction w t winter wtwinter@syr edu 215 jahn lab x6876
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Sugars and Polysaccharides. An Introduction W.T. Winter 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 215 Jahn Lab; x6876

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Sugars and Polysaccharides

An Introduction

W.T. Winter

215 Jahn Lab; x6876


  • Monosaccharides?

  • Oligosaccharides?

  • Polysaccharides

  • Glycoproteins and Proteoglycans

Carbohydrates Are Chiral Molecules

  • Typically but not always

  • L – amino acids

  • D - sugars


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



Fisher Formulas

Next to last carbon determines D or L

New carbon is added as C1

A Way to Explore Monosaccharides

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

Epimers Differ by Configuration at One Chiral Center

Sugars Prefer To Be Cyclic

Hemiacetals and Cyclization Group


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 rings can form chair and boat




  • 1-2 linked alpha glucose, beta fructose

  • Sources sugar cane

    sugar beet


  • 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

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.


Cellulose: Structural polysaccharide from glucose

n ~ 5000-10000

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


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

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



Extracellular Matrix: Hyaluronic acid

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

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

Other Structural Polysaccharides

  • Mannans – some algae

  • Alginic acids – many algae

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

  • Login