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4.4.1.4. Quaternary structure of proteins

Quaternary structure of proteins

The quaternary structure appears when the protein is made up of several polypeptide chains, whether or not they have a tertiary structure. Each of these polypeptide chains is called a protomer, monomer, or subunit.

These protomers are linked by weak bonds, such as hydrogen bondsVan der Waals forces, and even disulfide bridges, as is the case with immunoglobulins.

The collagen is a fibrous protein composed of three polypeptide chains intertwined to form helical larger triple helix conferring great resistance such fibers.

The hemoglobin (see bottom) is a globular protein comprised of four polypeptide chains.

Fundamental ideas about the quaternary structure of proteins

The Quaternary structure of proteins is the structure that occurs when the protein is made up of two or more polypeptide chains, whether they have a tertiary structure or not.

The subunits or protomers (polypeptide chains) that make up the quaternary structure are linked by weak bonds, such as hydrogen bonds,  Van der Waals forces , and even disulfide bridges, as is the case with  immunoglobulins.