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Penicillin amidase

About: Penicillin amidase is a research topic. Over the lifetime, 576 publications have been published within this topic receiving 15563 citations. The topic is also known as: penicillin amidohydrolase & ampicillin acylase.


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Journal ArticleDOI
TL;DR: In this article, an immobilized penicillin G acylase (PGA) was assembled in the interlayer galleries of a layered double hydroxide (LDH) by a three-step process.
Abstract: Immobilized penicillin G acylase (PGA) has been assembled in the interlayer galleries of a layered double hydroxide (LDH) by a three-step process. Glutamate-pillared LDH was first prepared by a novel process involving dissolution of an LDH-carbonate precursor in aqueous glutamic acid, followed by precipitation of the product by addition of base. This method avoids the problem of competitive intercalation by nitrate ions observed with conventional methods involving precipitation of LDHs from solutions of metal nitrate salts. The glutamate ions are strongly held in the interlayer region of the LDH by virtue of the electrostatic interaction between their carboxylate groups and the cationic layers, and act as carriers for the introduction and retention of free amino groups in the interlayer galleries. Subsequent reaction of the amino groups of the immobilized glutamate ions with a glutaraldehyde linker followed by addition of PGA affords the immobilized enzyme (IME). The intermediate and final materials, which can be termed bioinorganic nanocomposites, have been characterized by FT-IR spectra, powder X-ray diffraction (XRD) and thermal analysis. The activity, thermal stability, pH stability and operational stability of the IME have been assayed. After 10 recycles, carried out in succession in a discontinuous reactor, the IME displayed 90% activity retention, with the expressed activity remaining above 430 U/g.

58 citations

Journal ArticleDOI
TL;DR: A simple and versatile procedure to clone penicillin acylase genes has been developed that involves the construction of a plasmid library in a host presenting an amino acid auxotrophy and the production of those clones carrying the E. coli acyl enzyme was more sensitive to the growth temperature than that of the clones containing the K. citrophila gene.

58 citations

Journal ArticleDOI
TL;DR: In this article, the synthesis of ampicillin from phenylglycine methyl ester and 6-amino penicillanic acid (6-APA) with immobilized Escherichia coli PA in the presence of organic cosolvents was performed.
Abstract: Penicillin acylase (PA) is used in the industrial production of 6-amino penicillanic acid (6-APA). However, by proper control of reaction medium, the enzyme can be used in the reverse synthesis of β-lactam antibiotics from the corresponding β-lactam nuclei and suitable acyl donors. Under thermodynamically controlled strategy, the use of organic cosolvents can favor synthesis over hydrolysis by lowering water activity and favoring the non-ionic reactive species. Under kinetically controlled strategy using activated acyl donors, organic solvents can favor synthesis by depressing hydrolytic reactions. Results are presented on the synthesis of ampicillin from phenylglycine methyl ester and 6-APA with immobilized Escherichia coli PA in the presence of organic cosolvents. Several solvents were tested in terms of enzyme stability and solubility of substrates. Ethylene glycol, glycerol, 1–2 propanediol and 1–3 butanediol were selected accordingly and ampicillin synthesis was performed in all of them. Best results in terms of yield and productivity were obtained with ethylene glycol, with which further studies were conducted. Variables studied were enzyme to limiting substrate ratio, acyl acceptor to acyl donor ratio, organic solvent concentration, pH and temperature. Experimental design based on a two-level fractional factorial design was conducted. pH was determined as the most sensitive variable and was further optimized. The best conditions for ampicillin synthesis in terms of productivity, within the range of values studied for those variables, were pH 7.4, 28°C, 36 US PA/mmol 6-APA, 3 mol PGME/mol 6-APA and 45 % (v/v) ethylene glycol concentration. Productivity was 7.66 mM ampicillin/h, which corresponds to a specific productivity of 7.02 μmol ampicillin/h US at 55 % yield. Productivity was lower than in buffer but product yield was higher because of the much lower relative hydrolysis rates.

58 citations

Journal ArticleDOI
TL;DR: The synthesis of ampicillin catalyzed by Escherichia coli penicillin acylase was optimized in an aqueous system with partially dissolved antibiotic nucleus 6-aminopenicillanic acid (6-APA) using a mathematical model which showed that by increasing the amount of added substrates a nearly quantitative conversion of 6- APA and 85% conversion of acyl donor intoAmpicillin could be achieved.
Abstract: The synthesis of ampicillin catalyzed by Escherichia coli penicillin acylase was optimized in an aqueous system with partially dissolved antibiotic nucleus 6-aminopenicillanic acid (6-APA). The yields of both 6-APA and acyl donor could be improved by repetitively adding substrates to the reaction, allowing the concentration of 6-APA to remain saturated throughout. In this reaction concept, with four subsequent additions of substrates, 97% conversion of 6-APA and 72% of D-(-)-phenylglycine methyl ester (D-PGM) to ampicillin was achieved. The synthetic potential of this concept was estimated using a mathematical model which showed that by increasing the amount of added substrates a nearly quantitative conversion of 6-APA and 85% conversion of acyl donor into ampicillin could be achieved.

56 citations

Journal ArticleDOI
TL;DR: In this paper, the performance of stabilized derivatives of penicillin acylase has been tested in various water-cosolvent mixtures and the overall performance of the enzyme in the synthetic mode is a combination of two effects: (i) the inhibitory effect of the solvent on the enzyme and (ii) the desirable increase in the nonionized form of the substrate in the presence of solvent.

56 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20234
20222
20183
20175
20165
20153