RESUMO
Studies on the partition and purification of penicillin acylase from Escherichia coli osmotic shock extract were performed in poly(ethylene glycol)-sodium citrate systems. Partition coefficient 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 1000 systems and long tie line at pH 6.9. Under these conditions 2.6-fold purification with 83% yield were achieved. Influence of pH on partition shows that is the composition of the system and not the net charge of the enzyme that determines the behaviour in these conditions. Addition of NaCl to PEG 3350 systems significantly increases the partition of the enzyme. Although protein partition also increased, purification conditions were possible with 1.5 M NaCl where 5.7-fold purification and 85% yield was obtained. This was possible due to the higher hydrophobicity of the enzyme compared to that of most contaminants proteins.
Assuntos
Citratos , Escherichia coli/enzimologia , Penicilina Amidase/isolamento & purificação , Polietilenoglicóis , Fenômenos Químicos , Físico-Química , Temperatura Baixa , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Peso Molecular , Pressão Osmótica , Penicilina Amidase/química , Fosfatos , Cloreto de Sódio/administração & dosagem , Cloreto de Sódio/farmacologia , Citrato de SódioRESUMO
A number of simple azo dyes was degraded in liquid aerated batch cultures by a strain of the yeast Candida zeylanoides. The standard decolorization medium contained glucose as a carbon and energy source, and its pH was either controlled to 5.0-5.2, or allowed to decrease to 3.2-2.8, in the course of microorganism growth. The extent of colour removal in the culture medium was assessed through the decrease in dye absorbance of the supernatants. The extent of colour removal ranged from 44 to 90%, after 7 days, for 5 out of 6 dyes studied in shaked cultures, without pH control, and from 46 to 67%, after 22 hours, for 6 out of 8 dyes in batch experiments, at controlled pH.
Assuntos
Compostos Azo/metabolismo , Candida/metabolismo , Corantes/metabolismo , Compostos Azo/química , Biodegradação Ambiental , Candida/crescimento & desenvolvimento , Corantes/química , Meios de Cultura , Concentração de Íons de Hidrogênio , CinéticaRESUMO
The influence of phase volume ratio on partition and purification of penicillin acylase from Escherichia coli on poly(ethylene glycol)-sodium citrate aqueous two-phase systems was studied. In PEG 1000 systems both partition coefficients of the enzyme and total protein increased with decreasing phase volume ratio. However, in PEG 3350 containing NaCl, penicillin acylase follows a reverse trend, while total protein behaves in the same way. Implications for protein purification designs are discussed.