Table 2.
Binding parameters obtained by frontal analysis for tolbutamide with HSAa
| One-Site Model | Two-Site Model | Three-Site Model | |
|---|---|---|---|
| Ka1 (M−1) | 8.2 (± 0.4) ×104,b | 8.7 (± 0.6) × 104 | 1.1 (± 0.9) × 105 |
| mL1 (mol) | 2.4 (± 0.1) × 10−8,b | 2.0 (± 0.1) × 10−8 | 1.3 (± 2.0) × 10−8 |
| Ka2 (M−1) | 8.1 (± 1.7) × 103 | 2.6 (± 6.5) × 104 | |
| mL2 (mol) | 1.8 (± 0.1) × 10−8 | 1.7 (± 0.6) × 10−8 | |
| Ka3 (M−1) | 5 (± 149) × 102 | ||
| mL3 (mol) | 4 (± 97) × 10−8 | ||
|
Correlation Coefficient |
0.998c | 0.999 | 0.999 |
|
Sum of residuals squared |
3.9 × 10−18,c | 4.3 × 10−20 | 2.9 × 10−20 |
a
All of these parameters are for data obtained at pH 7.4 and 37 °C. The values in parentheses represent a range of ± 1 S.D (n = 9), as based on regression using Excel and the linear region of a plot made according to Eqn. (1) for a single-site model or the standard error as calculated by DataFit for a fit made according Eqn. (4) for a two-site or a similar expanded expression for a three-site model.
b
The Ka1 and mL1 values given for the one-site model were estimated from the linear region of a plot made according to Eqns. (1) or (5).
c
The correlation coefficient and sum of residuals squared given for the one-site model are for a fit of the entire data set to Eqn. (2).