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Titolo:
Kinetically controlled synthesis of ampicillin with immobilized penicillinacylase in the presence of organic cosolvents
Autore:
Illanes, A; Fajardo, A;
Indirizzi:
Univ Catolica Valparaiso, Sch Biochem Engn, Valparaiso, Chile Univ Catolica Valparaiso Valparaiso Chile ochem Engn, Valparaiso, Chile
Titolo Testata:
JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
fascicolo: 4-6, volume: 11, anno: 2001,
pagine: 587 - 595
SICI:
1381-1177(20010122)11:4-6<587:KCSOAW>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
BETA-LACTAM ANTIBIOTICS; SUBSTRATE-SPECIFICITY; THERMAL INACTIVATION; CATALYZED SYNTHESIS; ENZYMATIC-SYNTHESIS; N-PROTECTION; SOLVENTS; ENZYMES; ENANTIOSELECTIVITY; EQUILIBRIUM;
Keywords:
penicillin acylase; ampicillin; organic solvents; beta-lactam antibiotics; enzymatic synthesis;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Illanes, A Univ Catolica Valparaiso, Sch Biochem Engn, Av Brasil 2147, Valparaiso, Chile Univ Catolica Valparaiso Av Brasil 2147 Valparaiso Chile hile
Citazione:
A. Illanes e A. Fajardo, "Kinetically controlled synthesis of ampicillin with immobilized penicillinacylase in the presence of organic cosolvents", J MOL CAT B, 11(4-6), 2001, pp. 587-595

Abstract

Penicillin acylase (PA) is used in the industrial production of 6-amino penicillanic acid (6-APA). However, by proper control of reaction medium, theenzyme can be used in the reverse synthesis of beta -lactam antibiotics from the corresponding beta -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 andtemperature. Experimental design based on a two-level fractional factorialdesign was conducted. pH was determined as the most sensitive variable andwas 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 degreesC, 36 U-S 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 mu mol ampicillin/h U-S at 55 % yield. Productivity was lower than in buffer but product yield was higher because of the much lower relative hydrolysis rates. (C) 2001Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/04/20 alle ore 05:45:19