Oktamer

An octamer, sometimes spelled oktamer in some languages, is a molecular assembly consisting of eight subunits. The eight components may be identical or consist of different types that together form an eight-member complex. The term is used across biology, chemistry and materials science to emphasize the number of components rather than a specific structure.

In biology, a canonical example is the histone octamer, which forms the core of the nucleosome around which DNA is wrapped. It is composed of two copies each of histones H2A, H2B, H3, and H4, assembling into a roughly cylindrical core that interacts with about 147 base pairs of DNA in chromatin.

Beyond chromatin, cells often form octameric protein complexes involved in processes such as transcription, replication and DNA repair. Octameric assemblies can take various shapes, including ring- or torus-like structures, depending on subunit identity and interactions.

In chemistry and materials science, octamers describe eight-unit supramolecular assemblies, which can arise from coordination chemistry, host–guest chemistry, or designed macrocycles. Such octameric motifs are used as building blocks for self-assembled nanoscale materials and functional complexes.

Overview: the concept of an octamer is general and taxonomic, referring to eight constituent parts. The term highlights stoichiometry rather than a single universal architecture, leading to diverse forms across disciplines.