1. Four Levels of Protein Structure

2. Four Levels of Protein Structure
Primary Structure:
Linear Sequence of Amino Acids
Each amino acid has
central carbon liked to
---hydrogen (H)
---amino group (NH2)
---acid group (COOH)
---unique group (R) O H
H2N C C R OH

4. The carboxyl group of one amino acid is linked to the amino group of the next amino acid.

5. Four Levels of Protein Structure
Primary Structure:
Amino Acids are linked with a covalent bond called a peptide bond. O H H H O
H2N C C N C C OH R1 R2

6. Four Levels of Protein Structure
Secondary Structure:
Folded structure due to hydrogen bonds between the amino and acid groups of amino acids N C N C H H O O or O H O H C N C N

7. Four Levels of Protein Structure
Tertiary Structure:
Three dimensional folded structure due to attractions and repulsions between R groups
All but peptide bonds are involved in tertiary structure.

9. Four Levels of Protein Structure
Quaternary structure:
Association of two or more protein chains
eg. Hemoglobin is composed of protein chains
2 are called alpha hemoglobin are called beta hemoglobin