Histones are rich in basic amino acids residue lysine and arginine with charged side chain.  There are five types of histone proteins i.e., $H_1$, $H_{2A}$, $H_{2B}$, $H_3$ and $H_4$. Four of them occur in pairs to produce a unit of $8$ molecules (histone octamer)  The $\text{pH}$ of histones is basic.