How its protein structure related to its function?

Question

How its protein structure related to its function?

Answer 1

The relationship between structure and function of proteins is still a topic of research by biochemists.  Proteins are polymers (chains) of amino acid subunits.  Each of the twenty naturally-occurring amino acids possesses a unique "side chain" structure.  So, it is the structure and properties of the side chain that determines the contribution that a given amino acid makes to the overall function of the protein.  Some side chains contain groups (i.e., hydroxyls, amino, or carboxyl) that function directly in the catalytic cycle of an enzyme reaction associated with that protein.  Side chains that contain a -SH group often form covalent bonds with other -SH groups elsewhere in the protein.  This is often very critical to maintaining a certain 3-dimensional shape to the protein that is essential for its catalytic or structural role.  Some groups bind cofactors or pigments that perform special functions in association with the protein.  

So, to talk about function of a protein one must also think of the structure.