1. Proteins
Genetic information in DNA codes specifically for the production of proteins
Cells have thousands of different proteins, each with a specific job 1 1

2. An overview of protein functions
Table 5.1 2 2

3. Enzymes
Are a type of protein that acts as a catalyst, speeding up chemical reactions
Substrate
(sucrose)
Enzyme
(sucrase)
Glucose OH
H O
H2O
Fructose
3 Substrate is converted
to products.
1 Active site is available for
a molecule of substrate, the
reactant on which the enzyme acts.
Substrate binds to
enzyme. 2
4 Products are released.
Figure 5.16 3 3

4. Polypeptides Polypeptides A protein
Are polymers (chains) of amino acids
A protein
Consists of one or more polypeptides 4 4

5. Proteins are made of monomers called amino acids
contain both carboxyl and amino groups
Differ in their properties due to differing side chains, called R groups 5 5

6. Twenty Amino Acids 20 different amino acids make up proteins NonpolarH
H3N+ C
CH3 CH
CH2 NH
H2C
H2N
Nonpolar
Glycine (Gly)
Alanine (Ala)
Valine (Val)
Leucine (Leu)
Isoleucine (Ile)
Methionine (Met)
Phenylalanine (Phe)
Tryptophan (Trp)
Proline (Pro)
H3C
Figure 5.17 S
20 different amino acids make up proteins 6 6

7. http://www.youtube.com/watch?v=QHvklS77_U0 7 Polar ElectricallyOH
CH2 C H
H3N+ O
CH3 CH SH
NH2
Polar
Electrically
charged –O
NH3+
NH2+
NH+ NH
Serine (Ser)
Threonine (Thr)
Cysteine
(Cys)
Tyrosine
(Tyr)
Asparagine
(Asn)
Glutamine
(Gln)
Acidic
Basic
Aspartic acid
(Asp)
Glutamic acid
(Glu)
Lysine (Lys)
Arginine (Arg)
Histidine (His) 7 7

8. Amino Acid Polymers Amino acids Are linked by peptide bonds
Dehydration reaction
Amino Terminus (end)
CarboxylTerminus (end) 8 8

9. Protein Conformation and Function
A protein’s specific conformation (shape) determines how it functions 9 9

10. Four Levels of Protein Structure
Figure 5.20 –
Amino acid subunits
+H3N Amino end o
Carboxyl end c
Gly
Pro
Thr
Glu
Seu
Lys
Cys
Leu
Met
Val
Asp
Ala
Arg
Ser
lle
Phe
His
Asn
Tyr
Trp
Lle
Primary structure
Is the unique sequence of amino acids in a polypeptide
The order of amino acids is determined by inherited genetic information 10 10

11. Sickle Cell Disease

12. Secondary structure Is the folding or coiling of the polypeptide
Results from interactions between amino acids (NOT THE R-GROUPS)
Includes the  helix and the  pleated sheet held together by hydrogen bonds H
Figure 5.20 12 12

13.  helix – bonds between every 4th amino acid
 pleated sheet – when 2 or more regions of the chain line up parallel O C
 helix
 pleated sheet
Amino acid subunits N H R

14. Is the overall three-dimensional shape of a polypeptide
Tertiary structure
Is the overall three-dimensional shape of a polypeptide
Results from interactions between R groups
CH2 CH
O H O C HO
NH3+ -O S
CH3
H3C
Hydrophobic interactions and van der Waals interactions
Polypeptide backbone
Hyrdogen bond
Ionic bond
Disulfide bridge 14 14

15. Quaternary structure
Is the overall protein structure that results when two or more polypeptides subunits come together
Polypeptide chain
Collagen
 Chains
 Chains
Hemoglobin
Iron
Heme
Hemogloblin – 4 polypeptides, each has a heme group that holds oxygen 15 15

16. Review of Protein Structure
+H3N
Amino end
Amino acid
subunits
helix 16 16

17. A protein’s shape (conformation) also depends on the physical and chemical conditions of the protein’s environment
E.g. Temperature, pH, etc. affect protein structure 17 17

18. Denaturation occurs when a protein unravels and loses its native conformation (shape), rendering it unable to carry out its biological functions
Denaturation
Renaturation
Denatured protein
Normal protein
Figure 5.22 18 18