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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