Tertiary Structure
The tertiary structure is formed when the secondary structures (alpha helices and beta pleated sheets) fold up to form a very precise three-dimensional structure.
The forces which hold the tertiary structure are:
- Hydrogen bonds
- Ionic bonds
- Disulphide bonds
- Van der Waals forces
Hydrogen bonds
These bonds form between O– and H+
Where the shared electrons spend longer, there is a slight negative charge.
These bonds can be split using high temperatures and altered pH.
Ionic bonds
These bonds form between acids groups and basic groups.
They are also stronger than hydrogen bonds.
Ionic bonds are split by changing the pH.
Disulphide bonds
Disulphide bonds are covalent bonds which form between sulphur atoms
These bonds are stronger than hydrogen and ionic bonds
Reducing agents are used to split these bonds
Van der Waals forces
These are weak forces of attraction between non-polar groups
The water excluded from these hydrophobic side chains, helps to keep the side chains together
Van der Waals forces can be split by a rise in temperature
NOTE: anything with rings, -OH and NH3 is polar