Exhibits significant levels of protein deacetylase activity comparable to those of eukaryotic HDACs in assays both with fluorogenic peptidic substrates and acetate-radiolabeled histones. Accepts proteins with epsilon-acetylated lysine residues and tritiated-acetate-prelabeled chicken histones as substrates. The natural substrate protein is not yet known. Binds 1 zinc ion per subunit. Zinc, and cobalt and nickel at a lesser extent, are able to increase the catalytic activity (2.2-, 1.3- and 1.1-fold respectively) at concentrations of 1 mM. Higher concentrations have an inhibitory effect. Magnesium, manganese and calcium have no effect on activity at concentrations between 0 and 10 mM. At 100 mM, the catalytic activity is increased between 1.2- and 2.1-fold. Hydroxamates like TSA and SAHA inhibit the enzyme (PubMed:15060035). Is also inhibited by azobenzenes, stilbenes and arylazopyrazoles (PubMed:27756124). Optimum pH is 8.0. Homotetramer; dimer of dimers. Belongs to the histone deacetylase family.