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 16 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 Class
1. 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.