BIOSCI 107 Special topics 2

What are proteins?

Large molecules that are made up of C, H, N, O and sometimes S. They have specific shapes which give them specific functions in the body

Main types of proteins

Structural, catalytic, regulatory, immunological, contractile/motor

General amino acid structure

Amino group, carboxyl group, and R-group (side chain) bonded to a central carbon

4 levels of protein structure

primary, secondary, tertiary, quaternary

Primary structure

sequence of amino acids

Secondary structure

Either an alpha helix or beta pleated sheet.

Tertiary structure

3D resulting from interactions between side chains.

Quaternary structure

Multiple polypeptide chains forming a functional protein, interactions between side chains.

Side chain interactions

Hydrogen bonds, hydrophobic interactions, electrostatic interaction, disulfide bonds

Factors that cause protein denaturing

pH, temperature and salt concentration

2 general shapes of proteins

globular and fibrous

Fibrous proteins

long parallel strands, insoluble in water, used for structure

Globular proteins

spherical, water-soluble proteins.