FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 1 of 7
I) Carbohydrate Basics
a. Carbohydrates and its contents.
II) Carbohydrate (overview)
a. Carbohydrates are an important group of compound, biological molecules.
b. More carbohydrates in biosphere than anything else. (More than protein or fat, etc.)
c. They are simple component of all living things.
d. Can range from simple, three carbon molecules to complexes that are hundreds of millions of
molecular weight large.
e. There are metabolic intermediates like energy.
f. Everything alive contains carbohydrates (Including viruses because DNA and RNA contain sugar).
g. When carbohydrates bind to proteins they are called glycoproteins and when they bind to lipids
they are called glycolipids.
III) Carbohydrates-Saccharides-Sugars
a. The name comes from the structure. Carbohydrates were found to have equal amounts of Carbon
and Oxygen. It contained about twice as much Hydrogen. It was thought to be hydrates of Carbon
(which they are not).
b. However, they really are polyhydroxy aldehydes and ketones.
c. When the sugar is an aldehyde, it is called an alodose. When the sugar is a ketone, is called a
ketose.
d. The structure is named after the amount of carbons it has. For example, D-Glucose and DFructose both have 6 Carbons. D-Glucose is an aldohexose and D-Fructose is ketohexose. 5-Carbon,
D-Xylose, is an aldopentose and 3-Carbon, Dihydroxyacetone is a ketotriose.
IV) Optical Activity
a. How did optical activity arise? When a molecule exists in two different forms that aren’t
superimposable, then you have optical activity.
V) Chirality and Optical Activity
a. The right hand and left hand are similar but do not superimpose over the other. Similarly, when
you have a carbon with four different things attached they are not superimposable, no matter how
you twist.
b. When you have molecules like these, one will rotate light to the left, while the other would
rotates light to the right.
VI) Carbohydrates-Saccharides-Sugars
a. An asymmetric carbon is a carbon with 4 different Carbons attached.
VII) Principle of the Three Point Landing
a. Why do people care about optical activity? In nature, enzymes, receptors, and hormones that
react with molecules will either react with one molecule or the other. It will sometimes react with
both. Imagine you have a hormone receptor or the active site of an enzyme and it is a tetrahedral, it
should land in what is known as three point landing. The three sides should match up perfectly
which is why usually only one isomer will bind.
VIII)
Geometric Formulas
FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 2 of 7
a. Fischer, father of carbohydrate chemistry. He was the first to figure out the structure of glucose.
He started by separating one carbon at a time and constructing it by adding one Carbon at a time
onto a three Carbon molecule.
b. The wedges on the structure imply that the carbonyl group is coming out towards you. The dotted
line implies that the group is going into the plane of the paper.
IX) Absolute Configurations of Sugars
a. Fischer Convention- If the molecule is flipped, it is no longer the same molecule. However, it can
be turned 90°but it will not sit on its sides.
b. The sugars are D or L depending on its configuration.
c. Sugars are numbered from the end with the carbonyl group. D or L is then considered based the
highest numbered asymmetric Carbon. If the carbonyl group is on the right, it is a D-sugar. If it is on
the left side, it is a L sugar.
X) Enantiomers and Diastereomers
a. Molecules with the same molecular formula and order of attachment of constituent atoms are
known as stereoisomers. If the stereoisomers are mirror images, they are known as enantiomers. If
you synthesize a mixture in the lab, you will end up with about half and half left and right handed
molecules known as a racemic mixture. These have almost identical chemical and physical
properties making them hard to separate. The process of separating them is known as resolving
racemic mixtures. This is necessary because usually only one form of the drug actually works.
b. Stereoisomers that are not mirror images are diastereomers. These have different physical and
chemical properties and are not difficult to separate.
XI) Slide 11
a. D-Glucose and L-Glucose are enantiomers because they are mirror images. L-Mannose and DGlucose are diastereomers because they are not mirror images.
XII) Resolution of a Racemic Mixture
a. Louis Pasteur was one of the first men to resolve racemic mixtures. He picked out the different
crystal forms of the molecules. Then he tested them, one turned light to the left and the other
turned light to the right.
XIII)
Slide 13
a. He does not expect us to know everything on the slide but to know that concept of the slide
which is that there are many different combinations for these sugars because of the many chiral
carbons that exist in them.
XIV)
Lobry de Bryun-van Ekenstein reaction
a. If you have a bottle of pure glucose and add a little alkaline, Sodium Carbonate or Sodium
Hydroxide, and leave for about an hour, you will see that it is not pure glucose anymore. You will
observe some mannose and some fructose.
b. The alkaline converts the sugar to what is known as enediols. It mixes up the sugar solutions.
XV) Oxidation
a. Bromine water will oxidate the carbonyl group to an aldonic acid because it is an aldose.
b. Ketoses are not oxidized.
FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 3 of 7
c. Initially, a molecule was placed in Bromine water to determine if it was an aldose or a ketose.
d. Both aldoses and ketoses can be oxidized by alkalines such as Ca2+. This is possible because
alkalines can interconvert ketoses to aldoses.
XVI)
Another Oxidation
a. If you use an oxidizing agent that is slightly more powerful like diluted HNO, you can oxidize both
ends of the sugar forming an aldaric acid.
XVII) Reduction
a. Carbohydrates can be reduced using NaBH3, along with some other reagants.
b. When you reduce an aldose, you get an alditol. This turns the aldehyde group into an alcohol.
c. If you reduce a ketose, the carbonyl group can be reduced on either side giving you two alditols.
XVIII) Maillard Reaction
a. When an amino group reacts with a sugar, you get these mixtures of compounds that are usually
brown and have instant flavor.
Examples- Toast (turning brown), mixture of butter and sugar, etc.
XIX)
Slide 19
a. Aldehydes react with alcohols to for Hemiacetal.
b. Hemiacetal is a carbon with two hydrogen atoms attached and one is a hydroxyl group.
XX) Slide 20
a. Sugars like glucose are both aldehydes and alcohols. Therefore they are able to fold. They fold to
form pyranose, an organic compound from pyran which is a six membered ring containing an oxygen
atom.
b. The linear form of D-glucose undergoes an intramolecular reaction to form a cyclic hemiacetal
and creates a new chiral carbon which can be pointing into the plane or pointing up out of the
plane.
XXI)
Fischer Projection Formulas
a. Most sugars are in the form of a six membered ring.
b. In the past, what we know as rings were thought to be straight lines like the image in the slides.
XXII) Slide 22
a. The molecule shown in the picture is another way of showing how the molecule looks. This
orientation of the molecule is more similar to how the molecule actually looks.
XXIII) Slide 23
Ketones and alcohols mix to form hemiketals.
XXIV) Slide 24
a. The image in the slide illustrates how the ketose and the fructose folds into a 5 membered ring
and creates a chiral carbon.
XXV) Slide 25
a. Shows image of β-D-Fructofuranose.
XXVI) Slide 26
a. Image of α-D-Fructofuranose.
XXVII) Slide 27
a. This image is another orientation of how the molecule looks.
FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 4 of 7
XXVIII) Slide 28
a. The slide shows that a 5 or 6 membered ring can be formed from D-Glucose.
b. The 1-Carbon can react with the hydroxyl group on 5-Carbon making Pyranose.
c. The 1-Carbon can also react with the hydroxyl group on 4-Carbon making Furanose.
XXIX) Anomerica Configuration
a. The leading group in the sugar is pointing up (out of the plane). In this example, it is Ch2OH. It is
the highest numbered carbon.
b. Since the hydroxyl group can point up or down, there has to be a way to differentiate them. In the
α form of an anomeric configuration, the hydroxyl group sits on the opposite side of the plane as the
highest numbered group.
c. In the β form, the hydroxyl group sits on the same side of the plane as the highest numbered
group.
XXX) Anomeric Configuration (cont)
a. Pyranose means the structure is a six-membered ring.
b. In the α-L-Fucopyranose and the β-L- Fucopyranose forms, the highest numbered carbon is going
down into the plane of the paper which makes it an L confirmation. The rules of determining which
is α or β still applies with reference to the highest numbered carbon.
XXXI) Mutorotation
a. lf you get a pure bottle of α-D-glucose and dissolve it in water and place it in a polarimeter, you
will see that it rotates it quite strongly to the right.
b. After leaving it overnight and checking its progress, you will notice that the angle decreases. This
is known as mutorotation.
c. β-D-glucose does the same process, however, the angles are found to be of less intensity.
d. In a solution that has been sitting overnight, you will have a mixture that is 1/3 of α form and 2/3
of β form. You will also have a small trace of the straight chain form,, which can slowly interconvert.
XXXII) Confirmation
a. Confirmational structures are those with one end pointing up and one end pointing. This is known
as the chair confirmation.
b. The boat form shows steric crowding. (Both of its ends point upward.)
c. There are 2 possible chair confirmations, 4 possible boat confirmations, 6 possible skew
confirmations (twisted structures), and 12 possible half chair confirmations.
XXXIII) Major Sugar Residues of Mammalian Glycoconjugates
a. The difference between α-D-Glucose and α-D-Mannose is that the hydroxyl group goes into
different planes on Carbon-2.
b. The difference between α-D-Glucose and α-D-Galactose is that the hydroxyl group on 4-Carbon
are pointing on the opposite side of the planes.
c. In α-D-N-Acetylglucosamine molecules, there is an acetylamine group on 2-Carbon, instead of a
hydroxyl group like in the previous structures.
d. The same goes for the α-D-Acetylgalactosamine molecule.
XXXIV) The Discovery of Honey
a. Honey was one of the first preserving sugars found.
FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 5 of 7
XXXV) Honey
a. Fruit juices are sweet, but they spoil over time.
b. Honey is mainly Fructose and contains some microscopic glucose crystals.
c. Honey is preserving because it has a very small amount of water and the osmolarity is so high that
bacteria cannot grow in it.
XXXVI) Slide 36
Fructose in honey is mostly six membered rings but it can be five membered rings as well.
XXXVII) Common Alditols
a. Alditols are used in sweets that don’t cause cavities.
b. These sugars are made by getting an aldose and reducing it.
c. Common Altidols: D-Glucitol, D-Mannitol, D-Xylitol, D-Glycerol, and D-Ribitol.
XXXVIII)
Phytate (S38)
a. Inositol is a six membered ring and every Carbon contains a hydroxyl group on it.
b. Inositol is not a real sugar but an honorary sugar.
c. The molecule can be structured so that each one of the hydroxyl groups has a phosphate group (6
Phosphate groups). This is known as phytic acid or phytate.
d. This concept is important because it is found in some seeds and beans, which are taken up by
humans and animals.
e. For non-ruminants, this is a problem because the phosphate groups cannot be removed from the
structure when taken in by these animals. For example, pigs and chicken need phosphate because
they cannot produce the enzyme to remove the phosphate from the structure.
f. Cows can remove the structure using the enzyme phytase.
g. In a process known as utrification, the phosphate from chicken and pig manure can be removed in
ponds making a bloom, which isn’t environmentally healthy.
h. Canadians have engineered what is known as the enviropig, where the saliva contains the enzyme
phytase.
i. Nutritionist worry about phytate because the phosphate will bind to things like Calcium and
Magnesium and would go straight through us, rather than being absorbed. This is considered antinutrient.
j. May be important in preventing cancer.
XXXIX) Slide 39
a. Hemiacetal can react with another hydroxyl group and you get an Acetal.
b. Similarly, a Hemiketal forms a Ketal when it reacts with another hydroxyl group.
XL) Slide 40
a. Sugar acetals are called glycosides.
b. if you get a glucose and dissolve it into methanol and acid with heat, you will get a mixture of
metal glycosides.
c. Glycosides no longer mutorotate. The molecule becomes stable when turned into a glycoside.
XLI) Slide 41
a. Lactose (galactose linked with glucose) is a disaccharide. Dissacharides have two sugars.
b. In slides, the bonds connecting is there to show both molecules.
FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 6 of 7
c. Lactose is a reducing sugar.
d. Maltose and Cellubiose are reducing sugars also.
e. Sucrose is linked head to tail while the others are head to head. It does not have any anomeric
carbon atoms and therefore is not a reducing sugar.
XLII) Slide 42
XLIII) Amygdalin
a. Has a cyanide group attached to it.
b. It is the bitter component in apricots and peaches.
XLIV) Laetrile
a. People thought it would be the magic cure for cancer about 15-20 years ago.
b. The theory at the time was that the sugar would be taken up by cancer cells and that it would
poison the cells.
XLV) Slide 45
XLVI) Slide 46
a. The slide contains molecules known as tetrasaccharide (4 sugars)
b. The structure has Sucrose with Galactose linked to Carbon-6 and another galactose linked to
another Carbon in the position 6.
c. Humans do not make enzymes, which cleave those galactose molecules and it passes through
small intestines to large intestines, where bacteria takes the groups off and creates gas and
flatulence.
d. Beano (medicine) cleaves off galactose groups.
XLVII) Oligosaccharides
a. Do not need to know molecules on this slide. Know that the human milk contains a lot of these
oligosaccharides. They sometimes contain long chains of them.
b. Oligosaccharides are not found in cow milk.
c. Also found in babies urine. It is believed that these sugars prevent adherence of bacteria in babies
urinary tracts, but has been proven.
XLVIII) Glycosyl Transferase and Sugar Nucleotides
a. Biochemically, it is unfavorable to enzymatically attach more than one sugar. Sugars have to be
activated using nucleotides sugars.
b. It is activated by UDP.
c. Some other sugars use GDP.
XLIX) Slide 49
L) Lactose Biosynthesis
a. Men and women both have the enzyme galoctosyl transferase.
b. It catalyzes the addition of galactose to glucosamine.
c. In lactating mammary gland α-lactalbumin binds to the galactotosyl transferase changes its
enzymatic speciticity, allowing the enzyme to add galactose to glucose, making lactose. (Ex. of
lactose protein)
LI) Lactose Degradation
a. All children have the ability to breakdown lactose.
FUNDAMENTALS 1: 10:00-11:00
Scribe: CALVIN SIMS
WEDNESDAY, AUGUST 18, 2010
Proof: FARAH BUTT
PROFESOR: Pritchard
CARBOHYDRATE BASICS
Page 7 of 7
b. Lactose is major nutrient in all mammal milk.
c. β-galactosidase, in small intestine, cleaves Lactose into galactose and glucose.
d. As people get older, they produce less β-galactosidase. So lactose is not broken in the small
intestine but in the large intestine by bacteria (which creates gas). Produces CO2, H2, and all type of
smelly 2- and 3- carbon metabolites.
LII) Lactose Tolerance
a. These people are known to be lactose intolerant. Everyone produces different levels of βgalactosidase.
b. Depending on the area and ethnicity, people have different levels of the enzyme. Some parts of
Europe, Africa, and Asia tend to be less lactose intolerant because they drink a lot of milk as an adult
due to the production of dairy in their area.
LIII) The End (S53)