Figure 4.

Treatment of acetylated histone peptides with recombinant HOS3 (CBP-HOS3) results in site-specific deacetylation patterns. Fully acetylated peptides for each histone N-terminal tail were synthesized as described in Experimental Procedures. These were treated with recombinant CBP-HOS3 (peak fraction 28, Fig. 2A) for 5, 30, and 240 min with 1.2 μg of enzyme and analyzed by cHPLC-MS/MS as in Experimental Procedures. When applicable, the approximate amount of the detected ion compared with the total peptide is indicated for each site. When the value fell below the threshold of detection (≈5%), nd (not detected) is indicated. If the ion for the deacetylated species could be detected but a value could not be estimated accurately, present is indicated.