Table 3

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

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

Carenbauer et al. BMC Biochemistry 2002 3:4   doi:10.1186/1471-2091-3-4