Download Proteins Continued

Proteins Continued
–Tertiary Structure: refers to the overall 3-D shape of a protein produced from bending and folding stabilized by
interactions between side chains.
–Quaternary Structure: refers to the overall structure of proteins composed of more than one polypeptide chain.
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Mutations and Disease
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A gene that codes for a protein with one change in the amino acid sequence may be detrimental to the health of
the overall organism.
People who have sickle cell anemia have the 6th amino acid of two of the four polypeptide chain of the protein
hemoglobin replaced with a different amino acid. The ‘normal’ amino acid is glutamate, but in SCA it is replaced
with valine.
Replacement of a polar, charged amino acid with a nonpolar, uncharged amino acid causes red blood cells to
sickle as the valine is pulled inward and away from the hydrophilic environment in the bloodstream.
Other examples of genetic diseases: Tay-Sachs disease, Cystic fibrosis, Hemophilia
O
H2N
O
H2N
CH
C
CH
CH3
OH
CH
C
OH
CH2
CH2
C
O
CH3
OH
Valine
Glutamic acid
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Denaturation of Proteins
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When the structure of a protein has changed so that it can not perform it’s job as usual we say it has been
denatured.
The change is in the secondary, tertiary or quaternary structure, NOT the primary structure.
Causes of denaturation:
– Heat and UV Radiation
– Agitation
– Detergents
– Polar organic compounds
– Changes in pH
– Salts
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Vitamins
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Vitamins are organic compounds that are essential to our health and must be obtained through a good diet.
Some vitamins are water soluble while others are fat soluble:
– B and C vitamins are water soluble
– A, D, E and K are fat soluble
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Problems
1.
_____ are the building blocks of peptides and proteins.
2.
Are polar R groups on an amino acid hydrophobic or hydrophilic? What exactly does that mean?
3.
What two functional groups do ALL amino acids have in common?
4.
The two protein chains of insulin are held together by disulfide bonds. This is an example of the _____ structure of the overall
protein.
a.
Primary
b.
Secondary
c.
Tertiary
d.
Quaternary
e.
All of the above
5. The type of bond that is most important in maintaining secondary structure of a protein is
a.
disulfide bridges.
b.
hydrogen bonding within the backbone.
c.
hydrogen bonding between R groups.
d.
salt bridges.
e.
hydrophobic interactions.
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