scholarly journals Kinetics of reactive extraction of penicillin G by amberlite LA-2 in kerosene

AIChE Journal ◽  
2004 ◽  
Vol 50 (1) ◽  
pp. 119-126 ◽  
Author(s):  
Sang Cheol Lee
Keyword(s):  
Reactive Extraction ◽  
Penicillin G ◽  
Kinetics Of

scholarly journals Inactivation of penicillin acylase from Kluyvera citrophila by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline: a case of time-dependent non-covalent enzyme inhibition

1993 ◽  
Vol 291 (3) ◽  
pp. 907-914 ◽  
Author(s):  
J Martín ◽  
J M Mancheño ◽  
R Arche
Keyword(s):  
Enzyme Assay ◽  
Ph Dependence ◽  
Penicillin Acylase ◽  
Enzyme Inactivation ◽  
Time Dependent ◽  
Penicillin G ◽  
Reversible Binding ◽  
Ph Increase ◽  
Kinetics Of ◽  
Covalent Activation

Penicillin acylase (PA) from Kluyvera citrophila was inhibited by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ), a specific carboxy-group-reactive reagent. Enzyme activity progressively decreased to a residual value depending on EEDQ concentration. Neither enzymic nor non-enzymic decomposition of EEDQ is concomitant with PA inactivation. Moreover, enzyme re-activation is achieved by chromatographic removal of EEDQ, pH increase or displacement of the reagent with penicillin G. It was then concluded that PA inactivation is due to an equilibrium reaction. The kinetics of enzyme inactivation was analysed by fitting data to theoretical equations derived in accordance with this mechanism. Corrections for re-activation during the enzyme assay were a necessary introduction. The pH-dependence of the rate constant for EEDQ hydrolysis either alone or in the presence of enzyme was studied by u.v. spectroscopy. It turned out to be coincident with the pH-dependence of the forward and reverse rate constants for the inactivation process. It is suggested that previous protonation of the EEDQ molecule is required for these reactions to occur. The thermodynamic values associated with the overall reaction showed little change. Finally it is proposed that the inactivation of PA by EEDQ proceeds through a two-step reaction. The initial and rapid reversible binding is followed by a slow, time-dependent, non-covalent, reversible inactivating step. The expected behaviour in the case of enzyme modification by covalent activation of carboxy residues is also reviewed.

scholarly journals Antipneumococcal Activity of ABT-773 Compared to Those of 10 Other Agents

2000 ◽  
Vol 44 (7) ◽  
pp. 1894-1899 ◽  
Author(s):  
Todd A. Davies ◽  
Lois M. Ednie ◽  
Dianne M. Hoellman ◽  
Glenn A. Pankuch ◽  
Michael R. Jacobs ◽  
...  
Keyword(s):  
Ribosomal Protein ◽  
Vitro Activity ◽  
Penicillin Resistance ◽  
Penicillin G ◽  
23S Rrna ◽  
In Vitro Activity ◽  
Resistant Strains ◽  
Domain V ◽  
Kinetics Of

ABSTRACT MICs, time-kills, and postantibiotic effects (PAEs) of ABT-773 (a new ketolide) and 10 other agents were determined against 226 pneumococci. Against 78 ermB- and 44mefE-containing strains, ABT-773 MICs at which 50% of the isolates tested were inhibited (MIC50s) and MIC90s were 0.016 to 0.03 and 0.125 μg/ml, respectively. Clindamycin was active only against macrolide-resistant strains containing mefE (MIC50, 0.06 μg/ml; MIC90, 0.125 μg/ml). Activities of pristinamycin (MIC90, 0.5 μg/ml) and vancomycin (MIC90, 0.25 μg/ml) were unaffected by macrolide or penicillin resistance, while β-lactam MICs rose with those of penicillin G. Against 19 strains with L4 ribosomal protein mutations and two strains with mutations in domain V of 23S rRNA, ABT-773 MICs were 0.03 to 0.25 μg/ml, while macrolide and azalide MICs were all ≥16.0 μg/ml. ABT-773 was bactericidal at twice the MIC after 24 h for 8 of 12 strains (including three strains with erythromycin MICs greater than or equal to 64.0 μg/ml). Kill kinetics of erythromycin, azithromycin, clarithromycin, and roxithromycin against macrolide-susceptible strains were slower than those of ABT-773. ABT-773 had longer PAEs than macrolides, azithromycin, clindamycin, or β-lactams, including against ermB-containing strains. ABT-773, therefore, shows promising in vitro activity against macrolide-susceptible as well as -resistant pneumococci.

Equilibrium and Kinetics of Reactive Extraction of Propionic Acid Using Aliquat 336 and Tri-n-Butyl Phosphate in n-Hexanol

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Dr. Kailas L. Wasewar ◽  
Amit Keshav ◽  
Shri Chand
Keyword(s):  
Propionic Acid ◽  
Acid Concentration ◽  
Fermentation Broth ◽  
Reactive Extraction ◽  
Acid Extraction ◽  
Aliquat 336 ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pharmaceutical Industries ◽  
Kinetics Of

Recovery of propionic acid from different sources, like aqueous streams or from fermentation broth, is important in view of its wide usage in food, chemical and pharmaceutical industries. Reactive extraction is an emerging separation technique having numerous advantages like high selectivity and recovery. Effect of acid concentration, extractant concentration, pH, temperature and kinetics are the important steps in the reactive extraction. Equilibrium of propionic acid extraction using tri-n-butyl phosphate (TBP) and Aliquat 336 in n-hexanol respectively was carried out to find the better extractant out of the two for extraction of propionic acid. Aliquat 336 was found to be better than TBP with Ks = 2.2119 m3/kmol, thus indicating good complexation between it and the acid. The kinetics of extraction of the acid using Aliquat 336 in a stirred cell was investigated. The reaction was found to be first order in acid concentration and zero order in Aliquat 336 concentration. The reaction was found to be fast pseudo first order reaction occurring in the diffusion film and was found to be independent of hydrodynamics conditions. Rate constant was evaluated to be 163.398 1/s.

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