Article Figures & Data
Figures
- FIG. 1.
Ves (circles) and Vhs (triangles) of isoxazolylpenicillins in strain HN1157/pHSGoxa7. The rates were plotted against Cp, determined from the rates of hydrolysis in intact cells, as described in the text. Top, dicloxacillin; middle, cloxacillin; bottom, oxacillin.
- FIG. 2.
Ves (circles) and Vhs (triangles) of ureidopenicillins in strain HN1157/pHSGoxa7. The rates were plotted against Cp, determined from the hydrolysis rates in intact cells, as described in the text. Top, azlocillin; middle, mezlocillin; bottom, piperacillin.
- FIG. 3.
Ves (circles) and Vhs (triangles) of penicillin V and ampicillin in strain HN1157/pHSGoxa7. The rates were plotted against Cp, determined from the hydrolysis rates in intact cells, as described in the text. Top, penicillin V; bottom, ampicillin.
Tables
- TABLE 1.
Kinetic parameters of OXA-7 enzyme
Substrate % glucose used for growth $$mathtex$$\(\mathit{V}^{\mathit{max}}\)$$mathtex$$ (nmol/mg/s)a Km (μM)a Dicloxacillin 0.1 5.9 34 Cloxacillin 0.1 6.3 31 Oxacillin 0.1 9.3 52 Azlocillin 0 4.3 18 Mezlocillin 0 5.0 29 Piperacillin 0 3.5 34 Penicillin V 0.1 6.7 29 Ampicillin 0.1 4.1 21.5 ↵ a The values shown are the averages of three independent experiments. $$mathtex$$\(\mathit{V}^{\mathit{max}}\)$$mathtex$$ is the maximal rate of hydrolysis.
- TABLE 2.
Kinetic parameters of the efflux process
Substrate $$mathtex$$\(\mathit{V}_{\mathit{e}}^{\mathit{max}}\)$$mathtex$$ (nmol/mg/s) Hill coefficient K0.5 (μM) Permeability coefficient (μm/s) Substituent log Pa Dicloxacillin 0.98, 0.95, 0.94 3.6, 4.7, 4.3 0.53, 0.83, 0.82 0.6, 0.6, 0.6 3.4 Cloxacillin 0.89, 0.99, 0.80 2.3, 2.7, 2.4 0.95, 1.03, 0.91 0.6, 0.6, 0.6 2.8 Oxacillin 0.94, 1.1, 0.94 2.6, 2.7, 2.6 1.04, 0.97, 1.03 0.6, 0.6, 0.6 2.1 Azlocillin 0.42, 0.41, 0.35 4.0, 4.0, 4.6 1.08, 1.06, 1.09 0.4, 0.4, 0.4 0.71 Mezlocillin 0.51, 0.47, 0.50 4.4, 4.5, 4.5 1.09, 1.08, 1.11 0.5, 0.5, 0.5 0.67 Piperacillin 0.39, 0.35, 0.39 4.1, 3.7, 4.1 1.06, 1.08, 1.08 0.4, 0.4, 0.3 0.45 Penicillin V 0.72, 0.85, 0.72 4.7, 4.7, 4.6 0.82, 0.84, 0.83 0.8, 0.7, 0.7 1.54 Ampicillin 0.38, 0.37, 0.37 1.9, 2.3, 2.5 0.88, 0.92, 1.03 0.8, 0.8, 0.8 −1.03 ↵ a The log P values of the 6-substituent were calculated after the carboxyl group was changed to a methyl group at the website http://www.molinspiration.com/services/lopP.html .
- TABLE 3.
Predicted and measured MICs for HN1157/pHSGoxa7
Penicillin Cinh (μg/ml) MIC (μg/ml) Predicted Measured Dicloxacillin 18.4 (39)a 285 560 Cloxacillin 4.9 (11) 147 295 Oxacillin 4.8 (12) 135 282 Piperacillin 0.6 (1.2) 30 46 Azlocillin 0.6 (1.3) 40 44 Mezlocillin 0.6 (1.1) 33 30 Penicillin V 11.5 (33) 181 178 Ampicillin 1.0 (2.9) 26 39 ↵ a The numbers in parentheses are in μM.
