FIGURE 1.

Structures of HDAC inhibitors and time dependence on IC₅₀ values. A, chemical structures of 106 (top) and SAHA (bottom). B, IC₅₀ values for HDAC1 and HDAC3 with SAHA are independent of preincubation time (top). A preincubation time dependence of IC₅₀ values for inhibitor 106 was observed for both HDAC1 and HDAC3. The inhibitors and enzymes were preincubated for the indicated times, followed by addition of the acetylated lysine substrate. Deacetylation reactions were run for 1 h, and 5 mg/ml (final concentration) of trypsin developer was added.