TABLE 1.
Dissociation constants, enthalpy values, and entropy terms measured for the titration of ATAD3A-derived peptides into S100B and S100A1 using ITCa
| Protein | ATAD3A peptide residues (aa length) | Avg KD (nM) ± SD | Avg ΔHapp (kcal/mol) ± SD | Avg TΔS (kcal/mol) ± SD |
|---|---|---|---|---|
| S100B | 290-310 (21) | 620 ± 170 | −12.7 ± 0.5 | −3.9 ± 0.3 |
| S100B + Zn | 290-310 (21) | 200 ± 20 | −13.6 ± 0.1 | −4.1 ± 0.2 |
| S100B | 290-305 (16) | 630 ± 190 | −15.5 ± 1.1 | −6.6 ± 1.3 |
| S100B + Zn | 290-305 (16) | 390 ± 40 | −15.3 ± 0.5 | −6.2 ± 0.5 |
| S100B | 290-300 (11) | 3,360 ± 1,400 | −16.5 ± 0.6 | −8.7 ± 0.8 |
| S100B + Zn | 290-300 (11) | 720 ± 190 | −13.5 ± 1.7 | −4.8 ± 1.7 |
a
The solution included 10 mM TES, 15 mM NaCl, 100 mM KCl, 10 mM CaCl2, and 5% DMSO (pH 7.2) at 37°C. Where zinc is present, a concentration of 60 μM ZnAc was used. KD, enthalphy (ΔHapp), and entropy term (TΔS) parameters represent the average values of multiple experiments, with the standard deviations reported as the uncertainty. Ca2+-S100A1 binds ATAD3A-21 with a KD of 1.2 ± 0.7 μM and has a second weak-binding-site KD of >50 μM.