Table 2. Isothermal Titration Calorimetry of Human BRD9 with 9H-Purine Compounds^a.

ligand	[P] (μM)	[L] (μM)	KD (nM)	ΔHobs (kcal/mol)	N	TΔS (kcal/mol)	ΔG (kcal/mol)	LE
2a	740	30	no binding/weak
2b	385	30	no binding/weak
3a	477	26	8475 ± 237	–9.11 ± 0.12	0.99 ± 0.010	–2.42	–6.69	0.42
5b	392	30	no binding/weak
7a	385	34	641 ± 33	–12.71 ± 0.07	1.06 ± 0.004	–4.55	–8.16	0.45
7b	385	13.5	351 ± 18	–13.04 ± 0.07	0.97 ± 0.004	–4.52	–8.52	0.45
7c	378	14	297 ± 10	–12.05 ± 0.04	0.98 ± 0.003	–3.46	–8.59	0.45
7d	235	10	397 ± 19	–9.63 ± 0.06	0.97 ± 0.005	–1.18	–8.45	0.44
8a	381	18	7874 ± 258	–8.30 ± 0.15	1.06 ± 0.014	–1.57	–6.73	0.35
8b	392	30	no binding/weak
8e	451	32	7576 ± 365	–5.35 ± 0.09	1.05 ± 0.013	1.40	–6.75	0.36
9a	378	20	no binding/weak
11	381	30	278 ± 15	–10.28 ± 0.04	1.03 ± 0.003	–1.63	–8.65	0.43

^aTitrations were carried out in 50 mM HEPES, pH 7.5 (at 25 °C), 150 mM NaCl, and 15 °C while stirring at 1000 rpm. In both cases the protein was titrated into the ligand solution (reverse titration). Titrations were performed in triplicate. Ligand efficiencies (LE) have also been calculated where ΔG values were available (LE = ΔG/N where N is the number of non-hydrogen atoms).