The chemistry of amino acid side chains is critical to protein structure because these side chains can bond with one another to hold a length of protein in a certain shape or conformation.

Proteins are composed of one or more chains of amino acids, which are linked together by peptide bonds and folded into specific three-dimensional structures. Proteins have four levels of structure: ...

Protein folding requires chaperones and often involves stepwise establishment of regular secondary ... by hydrogen bonding and disulphide bridges, and then tertiary structure.