1. Protein Structure
Chapter 14

2. Protein Macromolecule
Proteins are polymers of amino acids (monomer)
Wide array of functions: hair, horn, skin, muscles, enzymes

3. Monomer: Amino Acid
Central carbon with an amino group, carboxyl group, hydrogen, and ‘R’ side chain
Same basic monomer, but differs at functional (R) side chain
20 different amino acids

4. The R-side chain
R-side chain gives each amino acid its distinct properties
EX. Acidic, Basic, Polar, Nonpolar
The R groups will determine the shape and characteristic of the protein

5. Protein Structure
Folding is crucial to the function of a protein and is influenced largely by the sequence of amino acids
The structure of a protein can be divided into several levels:
Primary (1o) structure
Secondary (2o) structure
Tertiary (3o) structure
Quaternary (4o) structure

6. Primary (1o) structure

7. Sequence and order of amino acid
Each amino acid is linked together by peptide (covalent) bonds

8. Secondary (2o) structure

9. Folding and twisting of the chain to form two structures
1) Alpha helix
2) Beta pleated sheets
These secondary structures are stabilized by hydrogen bonds between the amino acids

10. Tertiary (3o) structure

11. Three dimensional shape and folding of the polypeptide chain
Usually globular or spherical
Stabilized by different types of interactions and bonds
EX. Ionic, non polar, hydrogen, etc

12. Quaternary (4o) structure

13. Held together by the same types of bonds and interactions in the tertiary level BUT several tertiary structures interact together
EX: Hemoglobin, the protein in blood that carries oxygen, has four different subunits for its 4o structure

14. Protein Structure Review
Primary (1o) structure: sequence and order of amino acids bonded together by peptide bonds
Determines three-dimensional shape (2° and 3° structures)
Secondary (2o) structure: Alpha helix and beta sheets formed from hydrogen bonds
Tertiary (3o) structure: Bonds and interactions of R groups creating 3D structure
3o determines protein’s function
Quaternary (4o) structure: Multiple tertiary protein subunits bonded together