Protein Structure Levels

Proteins are large biochemical complexes that contain several polypeptide compounds (amino acid chains). They are organized into four levels of structure.

Primary structure

The chain of amino acids that make up the protein; this chain directly controls the other levels of protein structure.

Secondary structure

The patterns formed by segments of the polypeptide chain; can be either α-helices or β-pleated sheets.

Tertiary structure

The folding of the polypeptide to produce a certain shape.

Quarternary structure

The geometrical bonding of several polypeptides to form the protein.