What is a protein's overall function dependent on?

A protein's overall function is dependent on the shape of it. This is determined by four structural levels.

The primary structure of an enzyme is simply the sequence of amino acids.

The secondary structure represents how the peptide folds and twists on itself due to interactions between the amino acids. Secondary structures include coil-like alpha helices and beta pleated sheets , which resemble accordion folds.

The tertiary structure describes the overall folding of the whole peptide, with the secondary structures folding upon themselves to form a globular ball, the protein’s active conformation.

Some proteins have a quaternary structure that describes how two or more peptides combine to form a complex protein. For example, hemoglobin, which carries oxygen in the blood, is composed of four individual peptides that are linked to create a functional molecule. It would not be able to carry the iron ion without this structure. That is what then carries oxygen.