The stability of penicillin G during recovery by electrically enhanced extraction

Arnott, I.A.; Weatherley, L.R.

doi:10.1016/0032-9592(95)80017-4

Cited by 4 publications

(1 citation statement)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown by Arnott and Weatherley (1995), and Reschke and Schügerl (1984), KpenG degrades very easily because of the presence of a highly reactive and labile b-lactam ring that undergoes nucleophilic attacks.…”

Section: Kpeng Stabilitymentioning

confidence: 99%

Novel reactive perstraction system applied to the hydrolysis of penicillin G

Wyss

Seitert

Stockar

et al. 2005

Biotech & Bioengineering

View full text Add to dashboard Cite

The activity of penicillin acylase has been studied in aqueous and organic solvents, as free enzyme as well as immobilized within the membrane of liquid-core capsules. The activity of the enzyme is inhibited by the accumulation of the products of the hydrolysis reaction, namely phenyl acetic acid (PAA). In order to overcome this inhibition a range of organic solvents were tested for use in in situ product recovery. Of these solvents dibutyl sebacate (DBS) was chosen due to the rapid extraction rate, the high logP and to facilitate capsule production. The extraction efficiency at pH 3.5 for PAA was >80% for phase ratios of >50% free solvent with partition coefficients of 8 and 0.7 for PAA and penicillin G (PenG), respectively, thereby showing that PAA could be selectively extracted at pH 3.5 and 25 degrees C. Liquid-core capsules containing DBS were shown to efficiently remove PAA selectively and the PAA could be effectively back-extracted and the capsules re-used in a three-stage process resulting in high product separation. Immobilization of penicillin acylase onto the capsule membranes resulted in increased operational stability of the enzyme and a very high enzyme activity. Over 53.3% of the PAA formed could be recovered in the capsule core with a concentration over sevenfold higher than in the aqueous phase. Higher extraction efficiencies could be obtained by varying the substrate concentration and number of capsules. The enzyme immobilized on capsules could be stored for over 4 months at pH 8 and 4 degrees C with no loss of activity. Over 80% of the initial activity could be recovered over five repeated batch cycles of the bioconversion process. The importance of capsular perstraction and reactive capsular perstraction has been clearly demonstrated.

show abstract

Section: Kpeng Stabilitymentioning

confidence: 99%

Novel reactive perstraction system applied to the hydrolysis of penicillin G

Wyss

Seitert

Stockar

et al. 2005

Biotech & Bioengineering

View full text Add to dashboard Cite

show abstract

Electrically immobilized enzyme reactors: Bioconversion of a charged substrate. Hydrolysis of penicillin G by penicillin G acylase

Bossi¹,

Guerrera²,

Righetti³

1999

Biotechnol. Bioeng.

View full text Add to dashboard Cite

The possibility of using the multicompartment immobilized enzyme reactor (MIER) in presence of a charged substrate is here explored. Penicillin G acylase is used to convert penicillin G (a free acid, with a pK of 2.6) into two charged products: phenyl acetic acid (PAA, with a pK of 4.2) and 6‐aminopenicillanic acid (6‐APA, a zwitterion with a pI of 3.6). The enzyme is trapped by an isoelectric mechanism in a chamber of the electrolyzer delimited by a pI 5.0 and a pI 9.0 amphoteric, isoelectric membranes. Under normal operating conditions (continuous substrate feeding in the presence of an electric field), only a low substrate conversion can be achieved, due to rapid electrophoretic transport of unreacted penicillin G out of the reaction chamber towards the anode. Excellent conversion rates (>96%) are obtained under a “doubly‐discontinuous” operation mode: a time‐lapse substrate feeding, accompanied by short times (4–8 min) of electric field interruption. The product of interest (6‐APA, a precursor of semisynthetic penicillins), by virtue of its amphoteric nature, is trapped in a chamber delimited by a pI 3.5 membrane and a pI 5.5 membrane, adjacent to the reaction chamber on its anodic side. The other contaminant product (PAA) first accumulates in the same chamber and then progressively vacates it to collect in the anodic reservoir, leaving behind a pure 6‐APA solution. In this operation mode, vanishing amounts of unreacted substrate (penicillin G) leave the reaction chamber to contaminate the adjacent, anodic chambers. A novel class of zwitterionic buffers is additionally reported, able to cover very thoroughly any pH value along the pH 3–10 interval: polymeric, zwitterionic buffers, synthesized with the principle of the Immobiline (acrylamido weak acids and bases) chemicals. Enhanced enzyme reactivity is found in this macromolecular buffers as compared to conventional ones. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 383‐391, 1999.

show abstract

Reactive adsorption of penicillin on activated carbons

2010

View full text Add to dashboard Cite

A series of activated carbons with varied surface chemistry, obtained by wet oxidation and thermal treatment, was used for the removal of penicillin from low concentration aqueous solution. It was found that the carbon surface chemistry favors the degradation of the antibiotic, giving rise to various intermediates detected both in solution and in the adsorbed phase (deposited with the pore structure of the activated carbons). The confinement of penicillin molecules entrapped in the nanopores of activated carbons of acidic nature accelerates their degradation compared to that one in the bulk solution, which can be linked the strong local pH fall inside the pores. Degradation also takes place in activated carbons of basic pH, although the nature and partition of the intermediates formed differ from those in the acidic carbons. In both cases most of the breakdown products do not present therapeutic activity.

show abstract

The stability of penicillin G during recovery by electrically enhanced extraction

Cited by 4 publications

References 15 publications

Novel reactive perstraction system applied to the hydrolysis of penicillin G

Novel reactive perstraction system applied to the hydrolysis of penicillin G

Electrically immobilized enzyme reactors: Bioconversion of a charged substrate. Hydrolysis of penicillin G by penicillin G acylase

Reactive adsorption of penicillin on activated carbons

Contact Info

Product

Resources

About