What is the chemical nature and charge of Histone protein

🔑Key Points:
Histones are positively charged, basic proteins which are rich in Lysine and Arginine residues.
The histones H2A, H2B, H3 and H4 are involved in the nucleosome structure, while the H1 protein acts like a linker molecule between two nucleosomes.
2 molecules of H3 and H4 form a core of tetramer (as a pair of dimers).
This (H3)2.(H4)2 tetramer is associated with 2 independent dimers of H2A-H2B.
DNA being negatively charged, wraps around the histone octamer and forms the nucleosome.
DNA enters and leaves the same side and the two turns are sealed by the H1 protein.

🔴Additional Information:
The nucleosome model was proposed by Roger Kornberg for the DNA packaging in eukaryotic chromosome.
Nucleosomes are the first level of DNA condensation involved in DNA packaging.
A nucleosome contains about 200bp of DNA, out of which 146bp is involved in the coiling of octamers and the rest is associated with the linker molecule.
It forms the 11nm wide interphase fibre.