Complex sentence: Typically, these reactions are catalyzed by enzymes with "histone acetyltransferase" (HAT) or "histone deacetylase" (HDAC) activity, although it should be noted that HATs and HDACs can modify the acetylation status of non-histone proteins as well.
Split into simpler sentences: Typically, these reactions are catalyzed by enzymes with "histone acetyltransferase" (HAt) or "histone deacetylase" (HDAc) activity. Although it should be noted that HATs and HDACs can modify the acetylation status of non-histone proteins as well.