This product consists of a mixture of the native histone core proteins [H2A, H2B, H3 and H4] isolated from calf thymus.
Histones are set of DNA-binding basic proteins that are abundant in lysine and arginine residues located in the nuclei of eucaryotic cells. Histones H1, H2A, H2B, H3, and H4 form a core of two H2A-H2B dimers and a H3-H4 tetramer around which DNA winds to form nucleosomes — the basic repeating unit of chromatin in which 146 base pairs of DNA wrap twice around a histone octamer consisting of two copies of each of the core histones, H2A, H2B, H3, and H4. Two other histones, H1 and H5, serve as linkers. Histones protect DNA from damage and play important roles in gene regulation and DNA replication.
Histones can undergo post-translational modifications by methyl transferases, demethylases, acetyl transferases, deacetylases, phosphorylases and /or arginine deiminase. The latter converts arginine residues to citrulline residues, reducing the positive charge of target histones and thus reducing their affinity for DNA. Modifications to core histones influence chromatin organization and gene expression, providing for adaptive responses to environmental factors by epigenetic mechanisms.