2. What are Proteins?
Protein Structure
Protein Function
Diseases Associated with Proteins
OUTLINE
3. WHAT ARE PROTEINS?
We are exposed to proteins
every day of our life.
Part of many foods, along with
sugar, and fat.
Meat, milk, cheese, eggs are all
rich in protein.
When we ingest protein we break
it down into it’s component parts.
These parts are used to make
proteins we need and want.
4. WHAT ARE PROTEINS?
Machinery of the cell.
Vast array of functions:
◦ Oxygen Transport
◦ Metabolism
◦ Defence
◦ Cell Signalling
Two main types:
◦ Structural & Globular
Made of amino acids.
7. AMINO ACIDS
Proteins are made of small
compounds called amino acids.
There are only twenty different
amino acid molecules.
Each amino acid is similar in
size and composition, but each
of them unique.
Amino acids combine to form
dipeptides, and polypeptides.
Polypeptides are proteins.
PHENYLALANINE
TYROSINE
ISOLEUCINE
9. 4 LEVELS OF STRUCTURE
A protein molecule has
four levels of structure.
Primary Quaternary.
1° – Amino Acid
Sequence
2° – Small Local
Structure
3°–Assembly of 2°
Structure
4°–Assembly of 3°
Structure
Two main types of
secondary structure
called:
◦ Alpha-helix
◦ Beta-sheet
10. PRIMARY STRUCTURE
Amino acids combine to form a
polypeptide.
First step in making protein a
protein molecule.
Polypeptides can be as short as
10-20 amino acids, or as long
as 1,000 amino acids.
Large amount of variety
available in terms of which
amino acids are used.
DNA determines which amino
acids are used.
11. SECONDARY STRCUTURE
Primary structure of amino acids
folds on top of itself to form the
secondary structure.
Two main types of secondary
structure:
Alpha-helix – hollow tube
Beta-sheet - Flat panel
These structures provides from
shape and stability to a protein
molecule.
Silk, obtained from larvae of some
insects, 5X stronger than steel of
the same thickness.
13. TERTIARY STRCUTURE
Alpha helices and beta-sheet
structures combine.
Within the same protein
molecule you can have both
helices and sheets.
Regions of sheet and helix are
joined together by flexible
regions of linking amino acids.
Proteins are therefore strong
but flexible.
14. QUATERNARY STRUCTURE
Some proteins are composed
of multiple subunits.
The subunits are identical, and
combine to allow the protein to
do it’s job.
Allows an extra level of
regulation in the protein
function.
Example, Hemoglobin protein
for transporting oxygen.
16. PROTEIN FUNCTIONS
Vast array of proteins
performing a vast array of
functions.
Involved in:
◦ Immune system
◦ Oxygen Transport
◦ Eyesight
◦ Muscle Contraction
◦ Nervous system
They are the machines of
the cell. If there’s a job to be
done, it’s likely to involve a
protein.
19. HEME
OXYGEN TRANSPORT
Hemoglobin protein moves
oxygen around the body.
Composed of a protein part
called Globin, and a chemical
called Heme.
Uses an atom of Iron to help
bind to the oxygen atom.
Hemoglobin is present in large
amounts in red blood cells.
HEMOGLOBIN
20. CELL SIGNALLING
Proteins allow for
communication between
cells.
They act as receptor
molecules, imbedded in
the lipid bilayer of the cell.
Only interact with specific
molecules.
Once bound the signal is
sent, and the cells
behavior is modified.
21. ENZYMES
Enzymes are globular
proteins.
They are responsible
for chemical
modification within the
body.
Similar to an
autonomous robot
working in factory.
Can add/remove parts,
22. ENZYMES
Grab hold of molecules
inside or outside the cell.
Add or remove individual
atoms.
Change the structure, which
can result in a variety of
actions:
◦ Convert glucose to ATP
◦ Digest fats, sugars, proteins,
DNA
◦ Repair DNA
◦ Copy DNA
24. PROTEINS & DISEASE
Proteins were not thought to
cause disease.
Typically associated with
viruses, bacteria, fungi, and
parasites.
Changed in the 1980’s with the
discovery of Prions by Stanley
Prusiner.
Demonstrated proteins could
“infect” and self replicate with
requiring any control from
DNA.
25. PROTEINS & DISEASE
Proteins now known to be
associated with wide range of
debilitating diseases.
BSE in cattle, Scrapie in Sheep.
Huntington’s and Alzheimer's in
humans.
No cure, no treatment.
Difficult to diagnose, and difficult
to detect.
Collectively form Amyloid
Diseases.
26. PRION PROTEIN (BSE/CJD)
BSE is caused by a small
protein called PrP (Prion
Protein).
Small protein associated with
brain cell communication.
Two types of structure it can
form:
◦ Normal/folded
◦ Abnormal/misfolded
Abnormal form is very
sticky, results in large build
up protein molecules
Cytotoxic.
27. PRION PROTEIN (BSE/CJD)
Abnormal version of the protein
accumulates in the brain cell
death.
For cattle symptoms include:
◦ increased aggression
◦ sensitivity to sound/touch
◦ poor muscle coordination
For Humans, symptoms include:
◦ dementia, memory loss, hallucinations
◦ problems in speech and movement
◦ seizures
Patients survive between 2-5
years, but only know after ~1 year.
29. OTHER AMYLOID DISEASES
◦ Systemic Amyloidosis
Build up of protein material in the major organs of the
body
Heart and Liver are particularly susceptible
◦ Alzheimer’s Disease
Build of protein material in the brain
Typically occur later in life, 60’s-70’s
◦ Huntington’s Disease
Build up of protein in the brain
Occurs relatively early in life, 30’s
30. POSSIBLE TREATMENT
Antibody protein molecules.
Body utilizes them to attach
invading bacteria and
viruses.
Bind to protein coats of
viruses/bacteria, alert the
immune system.
Immune system destroys the
invaders.
BINDS TO VIRUS
ALERTS IMMUNE SYSTE
31. POSSIBLE TREATMENT
Antibodies are extremely
selective in what they bind
to.
Can tailor make them to
bond to anything we want
though.
So “raise” antibodies to
interact with proteins before
they covert to another
shape.
Works in theory, not yet a
therapy.
32. REVIEW
We ingest protein in our diet, in the form of milk, cheese, meats
and eggs.
We strip them down to their component parts, use them to make
our own proteins, or energy.
They have a wide variety of functions in the body.
Proteins can also cause disease, BSE, CJD, Huntington’s.
Very difficult to treat, and no known cures.
33. NEXT WEEK – FATS/LIPIDS
WHAT ARE FATS?
STRUCTURE AND
FUCNTION
FATS AND DISEASE
