Table 1.
Summary of cocaine and cocaine metabolites binding to both the intact antibody and the Fab fragment of the h2E2 mAb, as measured by quenching of intrinsic protein fluorescence.
| Cocaine | Benzoylecgonine (BE) | Cocaethylene (CE) | ||||
|---|---|---|---|---|---|---|
| Protein | 280 nm excitation | 295 nm excitation | 280 nm excitation | 295 nm excitation | 280 nm excitation | 295 nm excitation |
| KD (nM) | KD (nM) | KD (nM) | KD (nM) | KD (nM) | KD (nM) | |
| Intact h2E2 mAb | 2.52 ± 0.55 | 5.90 ± 1.39 | 19.1 ± 1.4 | 20.3 ± 1.9 | —* | 0.53 ± 0.11 |
| Fab fragment of h2E2 mAb | 1.60 ± 0.79 | 3.75 ± 1.63 | 16.2 ± 2.9 | 20.2 ± 5.3 | 0.65 ± 0.11 | 1.26 ± 0.24 |
Three or four titrations were performed to determine all drug-mAb affinities listed in the Table (reported as the mean ± standard deviation). All KD values were calculated as described in the Methods section.
*KD values not calculable, due to the absorbance at 280 nm of CE, leading to an inability to determine the ligand saturation plateau (fully quenched) fluorescence.