Tested Compound | Experimental Approach (Temperature) | |||||
---|---|---|---|---|---|---|
As Inhibitors (37°C) | As Substrates (30°C) | |||||
kIa (× 106 M−1min−1) | IC50b (nM) | k3 (min−1) | kI1 (× 106 M−1min−1) | kI2 (× 106 M−1min−1) | k3 (min−1) | |
rac-BMB | 8.30 (0.17) | 3.9 (0.6) | 0.01175 (0.0003) | 3.88 (0.90)c | 0.255 (0.071)c | 0.0064 (0.0004) |
R-BMB | 13.20 (0.74) | 2.7 (0.6) | 10.3 (6.9) | 0.482 (0.305) | ||
S-BMB | 3.23 (0.12) | 8.7 (0.9) | 1.56 (0.26) | 0. 091 (0.030) | ||
rac-MONO | 0.341 (0.019) | 44.7 (4.4) | — | 0.298 (0.183)c | ||
R-MONO | 0.839 (0.015) | 23.4 (2.8) | — | 0.544 (0.258) | ||
S-MONO | 0.215 (0.021) | 65.1 (9.6) | — | 0.127 (0.008) |
↵a These kI values are referred to as kI1 when the tested compound is bambuterol (BMB) and kI2 when it is bambuterol monocarbamate (MONO).
↵b Calculated from data measured after 60 min of incubation.
↵c Data obtained by using the simple hydrolysis model, which does not consider the kinetic competition between the two enantiomers (see Fig. 2A).