Table 1.
A summary of isothermal titration calorimetry (ITC) results in PBS at 20°C for cocaine and cocaine metabolite binding to the h2E2 anti-cocaine mAb. Thermograms obtained by injection of the respective ligands into the buffer alone were subtracted from the mAb ITC data before fitting the corrected data to obtain the parameters reported in the Table. The experimental errors for the binding parameters reported in the Table are all standard deviations derived from 4 independent ITC experiments performed with each ligand.
| Ligand Binding Parameter | Cocaethylene (CE) (n = 4) |
Cocaine (Coc) (n = 4) |
Benzoylecgonine (BE) (n = 4) |
Norcocaine (NC) (n = 4) |
Ecgonine Methyl Ester (EME) (n = 4) |
|---|---|---|---|---|---|
| N (# binding sites, per Fab present) | 0.922 ± 0.046 | 0.785 ± 0.032 | 0.901 ± 0.069 | 3.66 ± 0.07 | 1.90 ± 0.42 |
| K (association) (M−1) | 2.31E8 ± 1.3E8 | 1.33E8 ± 4.54E7 | 1.88E7 ± 3.26E6 | 704500 ± 36098 | 61375 ± 25024 |
| ΔH (cal/mol) | −13988 ± 279 | −15410 ± 368 | −15440 ± 833 | −3064 ± 150 | −2336 ± 452 |
| ΔS (cal/mol/deg) | −9.67 ± 1.98 | −15.4 ± 1.8 | −19.4 ± 2.5 | 16.3 ± 0.58 | 13.80 ± 2.33 |
| ΔG (cal/mol) | −11152 ± 302 | −10881 ± 187 | −9755 ± 106 | −7850 ± 27 | −6381 ± 247 |
| Kd (nM) | 5.29 ± 2.40 | 8.13 ± 2.37 | 54.4 ± 8.77 | 1422 ± 72 | 18708 ± 8313 |
| RBA (relative binding affinity, relative to the Kd for cocaine) | 0.65 | (1.00) | 6.7 | 175 | 2301 |