Quaternary structure

Representation of the structural levels of protein folding with a focus on the quaternary structure using the protein 1EFN

In biochemistry, a quaternary structure describes the defined arrangement of two or more macromolecules with a respective tertiary structure , which are held together by hydrogen bonds , van der Waals forces and Coulomb forces .

Quaternary structures made up of the same or similar subunits are called oligomers (or, according to the number of units, as dimers, trimers, etc.). One example is hemoglobin .

Structural levels subordinate to the quaternary structure are the primary structure , the secondary structure and the tertiary structure . This classification of the structure hierarchy was proposed in 1952 by Kaj Ulrik Linderstrøm-Lang .

Proteins

A classic example of quaternary structures are proteins , many of which can be assembled into functional complexes and reversibly separated. The association of the subunits takes place via hydrophobic interactions.

Proteins with a quaternary structure can be differentiated into:

• Fiber proteins (e.g. collagen , elastin , keratin )
• globular proteins (e.g. hemoglobin, myoglobin , ribosome)
• Protein complexes

Individual evidence

1. ↑ Entry on quaternary structure . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.Q05004 .