Table 2.
Parameters used in simultaneous fit of isotherms of a series of chelator containing solutions in HEPES buffer with residual ligand present
| Sample | Residuala Ca2+ (μM) | Purity (%) | K′Ca2+b (μM) | ΔH(cal/mol) |
|---|---|---|---|---|
| 5,5′ dimethylBAPTAc | ||||
| 16 | 564.7 | 69.8 | 0.129 | 2723 |
| Mixd | 553 | 69.8 | 0.129 | 2723 |
| EDTA | ||||
| 23 | 541.2 | 97.1 | 0.0269 | −6075 |
| Mixd | 553 | 97.1 | 0.0269 | −6075 |
a
Added Ca2+ derived from analytical preparation.
b
Ca2+ apparent dissociation constant for 5,5′-dimethylBAPTA and EDTA from potentiometric data analysis.
c
A (4.9%) percentage of the macromolecule described in the simulation is dedicated to a second chelator with a weak Ca2+ affinity of 18 μM and enthalpy of 1217.8 cal/mol to represent an apparent impurity (see the Supporting Material).
d
Sample is a 50:50 v/v mixture of samples 16 and 23.