Fig. 5. Two methods of preparation for chromatin used in immunoprecipitation of acetylated histones show similar patterns. (A) Comparison of the relative acetylation of histone H4 measured following two methods of preparation in 10 day chicken embryo erythrocytes. (B) The relative acetylation of Lys5 on histone H4 in 6C2 cells, compared for two different methods of chromatin preparation. In both (A) and (B), the black line shows data for chromatin that was fixed with 1% formaldehyde and sonicated to generate small fragments. The gray dashed line (data from Figure 3) shows results for chromatin prepared from nuclei digested with MNase and purified on a sucrose gradient to isolate mono- and dinucleosomes. Designations and map are the same as in Figure 3.