The tertiary structure is the overall 3D structure of one polypeptide chain. It describes the overall folding of the protein and the forces that influence this folding.
There is a subtle difference between secondary and tertiary structure.
The secondary structure only describes local folding of the protein, while the tertiary structure describes the overall structure of the protein.
The tertiary structure is influenced by the nature of interactions between amino acids brought together when the protein folds against itself. These amino acids may have many others in the chain between them, but be close in the folded 3D structure.
The following bonds are heavily involved in the tertiary structure:
- Ionic bond
- Hydrogen bond
- Disulphide bridge, a type of covalent bond that is unique to cysteine.
- Hydrophobic (or van der Waals) interactions