Chapter 7

Carbohydrates and Glycobiology

Chapter 7: Carbohydrates Learning Goals

1. Structures of “boxed” sugars: open chain and ring.

2. Amino- , deoxy- , and acidic sugars.

3. Common polysaccharides (amylose, amylopectin, cellulose, chitin, peptidoglycan).

4. Proteoglycans and glycan-domains…lectins.

5. Lipopolysaccharide.

6. Determination of sugar structure, glycosidic bonds.

Trioses

Hexose Models

Pentose Models

Three Carbon Sugars

Carbonyl on the End

Carbonyl Inner-Carbon

Epimers

Sugars: Carbonyl + Alcohol Ring Formation

Modified Sugars

Basis of Fehling’s Reaction = Glucose is Reducing

This is the more sensitive and specific test for glucose

EOC Problem 15: an exercise in recognizing reducing sugars.

Formation of Glycosidic Bond..Polysaccharides: Written from Non-Reducing to Reducing End

How Should This Really Be Drawn?

Fructose Turned Upside Down

This Glucose Should be Flipped Over

Sucralose - Sucrose Comparison

Sucralose is 600 times sweeter than Sucrose

Pardon the skeletized molecules . . Not showing all the atoms, you could fill them in.

What Is Sweet?

Tasting Panels: Taste Relative to Sucrose….dilutions of the test molecules.

Compound Sweetness

Lactose 0.16

Glycerol 0.60

Glucose 0.75

Sucrose 1.0

Fructose 1.75

Aspartame 250

Na-saccharine 510

Sucralose 600

Lugduname 225,000

Sweetner’s Calories

Because of sucralose intense sweetness, what is sold in the supermarket is mixed with a filler: fluffed glucose or fluffed maltodextrin. (Fluffed by the same process that makes Puffed Wheat or Puffed Rice breakfast cereals).

While sucralose can not be metabolized, the filler does have calories .. but less than 5 cal/gram. So the FDA allows the claim that sucralose products have no calories.

What is the nutritional calorie compared to the biochemical calorie?

What are the safety concerns?

Storage Polysaccharides

EOC Problem 20: How long can a game bird fly using its muscle glycogen? To solve this assume you have 1 gram of muscle tissue.

Glycogen and Starch…almost all α 1,4

Glycogen and Amylopectin have α 16 branches

Two cartoons of Amylopectin

Cellulose is Beta 1,4 linked

When aligned, they form H-bonds and fit like Leggo’s blocks to become insoluble.

EOC Problem 17 compares the solubility of glycogen and cellulose: both polymers of glucose, but different.

Cellulase is Only produced by Some Fungi and Some Bacteria

EOC Problem 19: The growth rate of bamboo, one of the fastest growing cellulose system in the

world.

Chitin – What are the modifications from cellulose?

OMG, Phi, Psy and Omega Angles on 1,6 Linkages

Ramachandran Redux

Amylose Helix

EOC Problem 18 compares the lengths of cellulose and amylose: both polymers of

glucose, but different.

Agarose

Peptidoglycan Has Interpeptide Bridges

Syndecan – Human Membrane Core Protein

Heparan is the same as Heparin with a few less sulfonates.

S-domains have 4 Functions

EOC Problem 23 has a good question about how heparin (which is not heparin) binds to antithrombin and demonstrates why clinical plastic and glassware is often coated with heparin.

Extracellular Matrix Proteolgycan

Atomic Force Microscopy

Carbohydrate Linkages to Protein

Gram Negative Bacterial Lipopolysaccharide

Be sure to do EOC Problem 27..determining branching in a polysaccharide

Mass Spectrometry of Oligos attached to a Protein

Things to Know and Do Before Class1. Know the structures of some of the “boxed” sugars.

2. Be able to diagram those with a ring conformation (Haworth projection) and which sugars are epimers of others.

3. Difference between a hemiacetal and a hemiketal.

4. Acetylated, phosphorylated, acidic, deoxy and amino sugars.

5. Making and breaking the glycosidic bond.

6. Fundamental structure of polysaccharides: amylose, amylopectin, cellulose, chitin, peptidoglycan, proteoglycans and lipopolysaccharide.

7. Determination of polysaccharide bonds.

8. EOC Problems 15, 17-20, 23, 27.