Porcine liver nuclear histone acetyltransferase. Partial purification and basic properties.

The major histone acetyltransferase activity from porcine liver nuclei has been isolated and partially purified by a simple, rapid, and reproducible method. Extraction of nuclei in buffered 30% saturated ammonium sulfate and subsequent ammonium sulfate fractionation, chromatography on DEAE-Sephacel and hydroxylapatite, and ultracentrifugation on linear 15-30% glycerol gradients provides an 8650-fold purification (over nuclei) in 42% yield. The molecular weight of the enzyme is approximately 94,000 as determined by glycerol gradient ultracentrifugation and gel filtration on Sephacryl S-200. The optimum pH for the reaction is 7.5 and the activity is inhibited by monovalent and divalent salts and by sulfhydryl blocking reagents. The enzyme activity is substantially protected from thermal denaturation at 37 degrees C by the addition of glycerol to the incubation medium. In the presence of the core histones, the enzyme catalyzes the acetylation reaction in the order H3 greater than H4 greater than H2B greater than H2A; the order for histones bound in nucleosome core particles is H4 greater than H2B greater than H3 greater than H2A. The high mobility group proteins 14 and 17 serve as substrates for the enzyme in vitro, suggesting a possible role for enzymatic high mobility group acetylation in chromatin function.