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. Author manuscript; available in PMC: 2012 Apr 1.
Published in final edited form as: Bioorg Med Chem Lett. 2011 Feb 2;21(7):2129–2132. doi: 10.1016/j.bmcl.2011.01.128

Figure 3.

Figure 3

Inhibition of wild-type and R37A HDAC8 by acetate. 0.4 μM wild-type (circle) and 10 μM R37A (triangle) Co(II)-HDAC8 were incubated with varying concentrations of sodium acetate (0 – 200 mM) in 25 mM Tris pH 8.0, 137 mM NaCl and 2.7 mM KCl for 5 min before initiating the reaction by addition of 50 μM substrate (R-H-K(Ac)-K(Ac)-fluorophore) (BIOMOL). Initial rates were determined from a change in fluorescence.20 The fractional activity is the ratio of the initial rate in the presence ((kcat/Km)Ac) and absence of acetate ((kcat/Km)0) (note that the activity of R37A HDAC8 is decreased >500-fold compared to WT HDAC8). The value of IC50 is calculated from fitting (kcat /Km)Ac /(kcat/Km)0 = 1 / (1 + [I]/ IC50) to the data.