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Table 3 Steady-state kinetic constants for hydrolysis of cephalosporins by wild-type L1 and L1 mutants.

From: Probing substrate binding to Metallo-β-Lactamase L1 from Stenotrophomonas maltophilia by using site-directed mutagenesis

  nitrocefin cefoxitin cefaclor cephalothin
Enzyme Km (μM) kcat (s-1) kcat/Km × 107 M-1 s-1 Km (μM) kcat (s-1) kcat/Km × 107 M-1 s-1 Km (μM) kcat (s-1) kcat/Km × 107 M-1 s-1 Km (μM) kcat (s-1) kcat/Km × 10-7 M-1 s-1
w.t. 4 ± 1 41 ± 1 1.0 1.1 ± 0.1 1.9 ± 0.1 0.17 13 ± 1 42 ± 1 0.32 8.9 ± 1.5 82 ± 5 0.92
S224A 7 ± 1 48 ± 5 0.69 3.0 + 0.5 1.0 ± 0.1 0.033 14 ± 2 14 ± 1 0.10 3.6 ± 0.1 19.8 ± 0.2 0.55
S224K 14 ± 2 48 ± 10 0.34 2.0 ± 0.3 0.60 ± 0.06 0.030 13 ± 2 6.5 ± 0.3 0.050 6.2 ± 0.6 26 ± 1 0.42
S224D 11 ± 5 2.3 ± 0.4 0.021 50 ± 6 1.4 ± 0.2 0.0028 215 ± 17 3 ± 1 0.0014 75 ± 7 32 ± 2 0.043
I164A 8 ± 2 130 ± 30 1.6 11 ± 1 8 ± 1 0.073 3.3 + 0.5 30 ± 3 0.91 16 ± 1 146 ± 2 0.91
F158A 123 ± 20 1290 ± 20 1.0 11 ± 2 16 ± 2 0.15 135 ± 23 99 ± 9 0.073 63 ± 17 353 ± 35 0.56
Y228A 23 ± 3 72 ± 2 0.31 10 ± 2 5.8 ± 0.3 0.058 550 ± 100 40 ± 3 0.0073 290 ± 60 320 ± 40 0.11
Y228F 36 ± 16 81 ± 18 0.23 8.2 ± 1.1 5.5 ± 0.5 0.067 240 + 60 74 ± 4 0.031 58 ± 7 190 ± 50 0.33
N233L 7 ± 2 62 ± 12 0.89 4.4 ± 1.6 0.90 ± 0.17 0.020 14± 2 32 ± 1 0.23 8.0 + 0.7 51 ± 1 0.64
N233D 9 ± 2 21 ± 2 0.23 1.1 ± 0.2 1.1 ± 0.1 0.10 25 ± 5 34 ± 3 0.14 18 ± 4 65 ± 2 0.36