"Histone acetylation and deacetylation" in the context of Assays & Kits refers to tools and reagents used to study modifications of histone proteins, particularly acetylation and deacetylation. Histone acetylation involves the addition of acetyl groups to specific lysine residues on histone proteins, affecting chromatin structure and gene expression. Histone deacetylation involves the removal of these acetyl groups.