TABLE 3.
Kinetic parameters of β-lactamases for Lek 157a
| Enzyme (model) | k2 (s−1) | K′ (μM) | k2/K′ (M−1 s−1) | kr (s−1) | kcat (s−1) | (ki)lim (s−1) | kcat/(ki)lim (k3/k4) | k3/k4 | Km (μM) | kcat/Km (M−1 s−1) | (ki)lim/Km (M−1/s−1) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Nmc-A (1a; substrate) | NDb | ND | ND | —c | 1.7 ± 0.1 (A) | — | — | — | 3.6 ± 0.2 (B) | (4.7 ± 0.1) × 105 (C) | — |
| TEM-1 (2c; inhibitor) | ND | ND | (5 ± 3) × 106 (C) | <5 × 10−5 (D) | 0.5 ± 0.05 (A) | (8 ± 0.5) × 10−4 (E) | 620 ± 70 (C) | 530 ± 10 (F) | 0.08 ± 0.04 (B) | (6 ± 3) × 106 (C) | (1 ± 0.5) × 104 (C) |
| BcII (Henri-Michaelis; substrate) | ND | ND | ND | — | 750 ± 150 (A) | — | — | — | 45 ± 10 (A) | (1.7 ± 0.5) × 107 (C) | — |
| 908R (2a′; inhibitor) | >0.2 (E) | >4 (E) | (36.5 ± 0.5) × 103 (E) | (4 ± 0.7) × 10−5 (D) | kr = k5 | — | — | — | ND | ND | — |
| OXA-10 (2a; inhibitor) | ND | ND | (7 ± 1) × 105 (E) | (5.6 ± 0.5) × 10−4 (D) | kr = k5 | — | — | 2.2 ± 0.1 (F) | 0.05 ± 0.01 (B) | (1.1 ± 0.25) × 104 (C) | — |
a
The capital letters in parentheses indicate the method used to obtain the value: A, measured directly under initial rate conditions; B, competitive inhibition; C, calculated (see text); D, residual activity measurements (reactivation); E, reporter substrate; F, measured directly in partial inactivation experiments.
b
ND, not determined.
c
—, not applicable.