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Table 2 Kinetic parameters determined with the purified OXA-205 β-lactamase

From: Purification and characterization of a new β-lactamase OXA-205 from Pseudomonas aeruginosa

Substrate

K m (μM)

k cat (s−1)

k cat /K m (M−1 s−1)

K i (μM)

n

x

Nitrocefin

6.9 ± 0.4

62.4 ± 3.3

9.09 × 106

   

Ampicillin

18.1 ± 0.6

36.4 ± 0.1

2.01 × 106

   

Carbenicillinb

360 ± 21

45.2 ± 1.9

1.26 × 105

2887 ± 56

2.1 ± 0.2

4.9 ± 0.7

Cefazolin

4.7 ± 0.3a

3.9 ± 0.1

8.25 × 105

   

Ceftazidime

NH

NH

–

   

Cefuroxime

30.4 ± 2.5

0.02 ± 0.001

6.69 × 102

   

Imipenem

0.02 ± 0.002a

0.03 ± 0.001

1.39 × 106

   

Meropenem

0.02 ± 0.002a

0.008 ± 0.0005

3.08 × 105

   

Oxacillinb

1369 ± 87

376 ± 25

2.75 × 105

1869 ± 75

1.1 ± 0.1

3.6 ± 0.2

Penicillin G

2.3 ± 0.06a

39.1 ± 2

1.68 × 107

   
  1. Reactions were carried out using the concentration of OXA-205 ranging from 2.5 to 814 nM. All values are the means of at least three different measurements
  2. NH no hydrolysis observed at a substrate concentration up to 1 mM
  3. – Not calculated
  4. aMeasured as an inhibition constant (Ki) in competition experiment against nitrocefin [13]
  5. bObtained data was fitted to the Eq. 2 because substrate inhibition kinetics were observed
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Annals of Clinical Microbiology and Antimicrobials

ISSN: 1476-0711

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