tetramer

A tetramer is a molecule composed of four structural subunits, such as peptide chains or condensed monomers. This term is frequently used in biology, particularly when discussing proteins.1

For example, human hemoglobin is a tetramer, consisting of four peptide chains: two alpha-chains and two beta-chains. These subunits are held together by noncovalent interactions like hydrogen bonds and hydrophobic interactions. The molecular weight of a typical mammalian hemoglobin tetramer is approximately 64,500. In contrast, myoglobin, another protein involved in oxygen transport, is a monomer, meaning it has only one subunit.23