Histone octamers are defined protein complexes composed of two copies each of core histones H2A, H2B, H3, and H4 assembled into the canonical octameric core that wraps approximately 147 bp of DNA to form the nucleosome. Recombinant or purified histone octamers provide homogeneous, ready-to-use building blocks for chromatin reconstitution, structural biology, biophysical assays, enzymatic studies, and assay development. Available as pre-assembled octamers (wild-type or variant/PTM-containing) or as components with validated refolding protocols, these reagents save time and improve reproducibility for nucleosome research.

Key Features

• Pre-assembled and validated: Supplied as fully assembled octamers or as individual purified histones with optimized refolding protocols.
• Variant and PTM options: Available as wild-type canonical octamers and variant-containing octamers (H2A.Z, H2A.X, H3.3, CENP-A), as well as octamers carrying site-specific post-translational modifications (PTMs) such as acetylation, methylation, phosphorylation, and ubiquitination.
• High purity and homogeneity: Purified through chromatography and optimized refolding procedures, typically achieving purity levels greater than 90–95%, and validated using native PAGE, SDS-PAGE, and mass spectrometry.
• Assembly on defined DNA: Compatible with the Widom 601 nucleosome positioning sequence, custom DNA fragments, or user-supplied sequences for mononucleosome and nucleosome array assembly.
• Tagged and engineered options: Available with epitope tags (His, FLAG), site-specific labeling sites (single cysteine), or fluorescent labels for single-molecule and FRET-based studies.
• Quality control: Lot-specific analyses include octamer integrity, histone stoichiometry, mass confirmation, and functional nucleosome assembly efficiency.

Common Applications

• Nucleosome reconstitution: Assembly of mononucleosomes and nucleosome arrays for biochemical, molecular, and biophysical investigations.
• Structural biology: Essential reagents for cryo-electron microscopy (Cryo-EM) and X-ray crystallography studies requiring homogeneous octamer samples with defined modification states.
• Chromatin remodeling assays: Substrates for ATP-dependent chromatin remodelers such as SWI/SNF, ISWI, and CHD complexes, enabling studies of nucleosome sliding, eviction, and remodeling kinetics.
• Enzyme assays: Defined substrates for histone-modifying enzymes, including histone acetyltransferases (HATs), histone methyltransferases (HMTs), kinases, and ubiquitin ligases, as well as for screening small-molecule modulators.
• Single-molecule and FRET studies: Fluorescently labeled octamers suitable for smFRET, optical tweezers, atomic force microscopy (AFM), and other high-resolution biophysical techniques.
• Immunoassay controls and antibody validation: Standardized octamers used for validating histone- and PTM-specific antibodies and for calibrating quantitative chromatin-related assays.