Chemical conformation

In biochemistry, the conformation of a protein is its structure.

There are four levels of conformation:

1. Primary conformation is the sequence of amino acids that are joined to form the protein's polypeptide chain(s).
2. Secondary conformation is the twisting of polypeptides to form alpha helices, beta sheets, and other shapes. These structures are held together by hydrogen bonds.
3. Tertiary conformation is the twisting of alpha helices and beta pleated sheets into larger structures, due to the formation of disulfide bridges, a weak form of chemical bond.
4. Quaternary conformation is the conjugation of two or more polypeptides to form a still larger structure.

A protein may have more than one conformation, and readily change from one to another. For instance, conformational changes of the myosin molecule cause muscle contractions. The binding of activator or inhibitor molecules to an enzyme causes it to change shape and activate or deactivate accordingly.