What is the relationship between protein structure and protein function?

Protein structure sets the foundation for its interaction with other molecules, which ultimately determines its function. Proteins fold up into specific shapes according to the sequence of amino acids in the polypeptide chain. If the specific 3D structure is disrupted, for which the protein is said to be denatured, the protein loses its activity. For example, denatured enzymes lose their catalytic ability, denatured antibodies can no longer bind antigen, and disrupted subunits cannot assemble into multimers to perform their functions. In a word, the protein function is directly dependent on the protein structure, which cannot be carried out once the structure is disturbed.