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Optimization of the culture medium composition using response surface methodolo...
Sampaio, Pedro N.; Calado, C.R.C.; Sousa, Lisete; Bressler, David C.; Pais, Maria Salomé; Fonseca, Luís PinaThe optimization of culture medium compositionwas carried out for improvement the recombinantcyprosin B production, an enzyme with high milk-clottingactivity. Response surface methodology (RSM) wasapplied to evaluate the effect of variables namely glucose,yeast extract (YE) and bactopeptone present in the culturemedium, used for recombinant cyprosin B production bytransformed Saccharomyces cerevisiae BJ1991 str...
Production of 6-aminopenicillanic acid in aqueous two-phase systems by recombin...
Cao, Xue-jun; Wu, Xing-yan; Fonseca, Luís Pina; Cabral, J. M. S.; Marcos, João CarlosBioconversion of Penicillin G in PEG 20000-Dextran T 70 aqueous two-phase systems was achieved using the recombinant Escherichia coli A56 (ppA22) with intracellular penicillin acylase as catalyst. The best conversion conditions were attained for: 7%(w/v) substrate (penicillin G), enzyme activity in bottom phase 52 U/ml, pH 7.8, temperature 37°C, reaction time 40 min. Five repeated batches could be performed in ...
Application of surface response analysis to the optimization of penicillin acyl...
Marcos, João Carlos; Fonseca, Luís Pina; Ramalho, Maria Teresa; Cabral, J. M. S.Penicillin acylase purification from an Escherichia coli crude extract using PEG 3350 – sodium citrate aqueous two phase systems was optimized. An experimental design was used to evaluate the influence of PEG, sodium citrate and sodium chloride on the purification parameters. A central composite design was defined centred on the previously found conditions for highest purification from an osmotic shock extract....
Partial purification of penicillin acylase from Escherichia Coli in poly(ethyle...
Marcos, João Carlos; Fonseca, Luís Pina; Ramalho, Maria Teresa; Cabral, J. M. S.Studies on the partition and purification of penicillin acylase from osmotic shock extract Escherichia coli were performed in poly (ethylene glycol)- citrate systems. Both partition behavior of the enzyme and total protein are similar to those described in other reports increasing ,with pH and tie-line length and decreasing with PEG molecular weight . However, some selectivity could be attained with PEG ...
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