Primary structure
The primary structure is the sequence of amino acids. This is not a protein, as it is not processed (folded), instead it is known as a polypeptide.
The primary structure is held by peptide bonds between the amino acids.
Secondary Structure
The secondary structure is where alpha-helices and beta-pleated sheets are formed. These form due to hydrogen bonding between different amino acids in the polypeptide chain.
Hydrogen bonds can form between:
- The -CO (carboxyl group) of one amino acid and the -NH (amine group) of another amino acid
- The -CO (carboxyl group) of one amino acid and the -OH (hydroxyl group) of another amino acid