Table 2. Thermodynamic parameters for the binding of Pb²⁺ to Tau_244–372 (or full-length Tau protein) as determined by ITC at 25.0°C.

Tau244–372	K d (µM)	n	(kcal mol−1)	(kcal mol−1)	(cal mol−1 K−1)
WT	0.217±0.029	1.090±0.003	−6.78±0.04	−9.08±0.08	7.73±0.39
H330A	82±48	0.59±0.32	−0.31±0.21	−5.79±0.36	17.7±1.8
H362A	0.546±0.020	0.165±0.047	−7.85±0.29	−8.53±0.22	2.32±1.72
DM	NB	–	–	–	–
TM	0.286±0.042	1.130±0.005	−6.19±0.05	−8.92±0.08	9.17±0.45
Histidine-less	NB	–	–	–	–
Full-length Tau	0.29±0.16	2.72±0.06	−7.86±0.30	−8.91±0.32	3.55±2.05

Thermodynamic parameters, Kd, , and n, were determined using a single set of identical sites model. The standard molar binding free energy () and the standard molar binding entropy () for the binding reaction were calculated using Equations 2 and 3 respectively.

The buffer used was 50 mM Bis-Tris buffer (pH 7.4). Errors shown are standard errors of the mean.

WT, wild-type Tau_244–372; DM, double mutant H330A/H362A of Tau_244–372; TM, triple mutant H268A/H299A/H329A of Tau_244–372; Histidine-less, histidine-less mutant H268A/H299A/H329A/H330A/H362A.

NB, no binding observed in the present conditions.