Download 6. Protein Hydrolysis and Denaturation

Chapter 19 Amino Acids and
Proteins
19.6
Protein Hydrolysis and Denaturation
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
1
Protein Hydrolysis
Protein hydrolysis
 splits the peptide bonds to give smaller peptides
and amino acids
 occurs in the digestion of proteins
 occurs in cells when amino acids are needed to
synthesize new proteins and repair tissues
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
2
Hydrolysis of a Dipeptide
 In the lab, the
hydrolysis of a peptide
requires acid or base,
water, and heat.
 In the body, enzymes
catalyze the hydrolysis
of proteins.
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
3
Denaturation
Denaturation involves
 the disruption of bonds in the secondary, tertiary,
and quaternary protein structures
 heat and organic compounds that break apart H
bonds and disrupt hydrophobic interactions
 acids and bases that break H bonds between polar
R groups and disrupt ionic bonds
 heavy metal ions that react with S—S bonds to form
solids
 agitation, such as whipping, that stretches peptide
chains until bonds break
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
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Applications of Denaturation
Denaturation of protein occurs
when
 an egg is cooked
 the skin is wiped with alcohol
 heat is used to cauterize
blood vessels
 instruments are sterilized in
an autoclave
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
5
Learning Check
What are the products of the complete hydrolysis of
the tripeptide Ala-Ser-Val?
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
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Solution
What are the products of the complete hydrolysis of
the tripeptide Ala-Ser-Val?
The products are the three amino acids: alanine,
serine, and valine.
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
7
Learning Check
Tannic acid is used to form a scab on a burn. An egg
is hard-boiled by placing it in boiling water. What is
similar about these two events?
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
8
Solution
Tannic acid is used to form a scab on a burn. An egg
is hard-boiled by placing it in boiling water. What is
similar about these two events?
Acid and heat cause the denaturation of protein.
They both break bonds in the secondary and tertiary
structures of proteins.
General, Organic, and Biological Chemistry
Copyright © 2010 Pearson Education, Inc.
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