Table 2.
Association equilibrium constants (KA), total binding capacity (mL) and specific activity for the probe candidate with HSA
| Probe Candidate | Association Equilibrium Constant, KA (M−1) |
Total Binding Capacity, mL (mol) |
Specific Activity (mol/mol HSA) |
|---|---|---|---|
| Indole-3-acetic acida | 3.4 (± 0.08) × 106 | 3.7 (± 0.05) × 10−8 | 0.78 (± 0.03) |
| Indole-3-carboxylic acida | 8.5 (± 0.2) × 103 | 12 (± 0.02) × 10−8 | 2.6 (± 0.1) |
| 3-Acetylindole | 7.8 (± 0.6) × 104 | 0.84 (± 0.01) × 10−8 | 0.18 (± 0.01) |
| Indole-3-propionic acid | 1.1 (± 0.02) × 105 | 4.5 (± 0.01) × 10−8 | 0.94 (± 0.04) |
| 3-Methylindole | 5.3 (± 0.5) × 104 | 2.9 (± 0.9) × 10−8 | 0.62 (± 0.19) |
| Indole-3-butyric acid | 9.7 (± 3.0) × 105 | 2.6 (± 0.2) × 10−8 | 0.55 (± 0.04) |
| Indole-3-methanol | 1.2 (± 0.5) × 105 | 0.12 (±0.05) × 10−8 | 0.03 (± 0.01) |
a
The results in this table were all obtained using a model based on a single major binding site. However, other data obtained in this report suggests that indole-3-acetic acid and indole-3-carboxylic acid may actually have significant multi-site binding with HSA, as discussed in the text.