ABSTRACT
The enzyme D-galactose dehydrogenase (GalDH) has been used in diagnostic kits to screen blood serum of neonates for galactosemia. It is also a significant tool for the measurement of β-D-galactose, α-D-galactose and lactose as well. In this study, response surface methodology (RSM) was used to identify the suitable conditions for recovery of recombinant GalDH from Pseudomonas fluorescens in aqueous two-phase systems (ATPS). The identified GalDH gene was amplified by PCR and confirmed by further cloning and sequencing. E. coli BL-21 (DE3) containing the GalDH gene on a plasmid (pET28aGDH) was used to express and purify the recombinant enzyme. The polyethylene glycol (PEG) and ammonium sulfate concentrations and pH value were selected as variables to analyze purification of GalDH. To build mathematical models, RSM with a central composite design was applied based on the conditions for the highest separation. The recombinant GalDH enzyme was expressed after induction with IPTG. It showed NAD+-dependent dehydrogenase activity towards D-Galactose. According to the RSM modeling, an optimal ATPS was composed of PEG-2000 14.0% (w/w) and ammonium sulfate 12.0% (w/w) at pH 7.5. Under these conditions, GalDH preferentially concentrated in the top PEG-rich phase. The enzyme activity, purification factor (PF) and recovery (R) were 1400 U/ml, 60.0% and 270.0%, respectively. The PEG and salt concentrations were found to have significant effect on the recovery of enzyme. Briefly, our data showed that RSM could be an appropriate tool to define the best ATPS for recombinant P. fluorescens GalDH recovery.
Subject(s)
/analysis , /genetics , /isolation & purification , Plant Extracts/isolation & purification , Pseudomonas fluorescens/chemistryABSTRACT
Objective: To optimize the extracting technology of assessing the maximum yield of phenolic compounds (PC) from Inonotus obliquus by single factor experiments and orthogonal array design methods through aqueous two-phase systems combined with ultrasonic extraction. Methods: The range of the independent variables, namely levels of acetone and ammonium sulfate, and ultrasonic time were identified by a first set of single factor experiments. The actual values of the independent variables coded at four levels and three factors were selected based on the results of the single factor experiments. Subsequently, the levels of acetone and ammonium sulfate, and ultrasonic time were optimized using the orthogonal array method. Results: The optimum conditions for the extraction of PC were found to use 7.0 mL acetone, 5.5 mg ammonium sulfate, with ultrasonic time for 5 min. Under these optimized conditions, the experimental maximum yield of PC was 37.8 mg/g, much higher than that of the traditional ultrasonic extraction (UE, 29.0 mg/g). And the PC obtained by this method had stronger anti-oxidative activities than those by traditional UE method. Conclusion: These results indicate the suitability of the models developed and the success in optimizing the extraction conditions. This is an economical and efficient method for extracting polyphenols from I. obliquus. © 2013 Tianjin Press of Chinese Herbal Medicines.
ABSTRACT
Bromelina é um nome coletivo para enzimas proteolíticas encontradas no talo, fruto e folhas do abacaxi (Ananas comosus Merr). A bromelina possui propriedades anti-inflamatórias, de debridamento, entre outras. Para a produção da bromelina deve-se, preferencialmente, usar resíduos do abacaxi, visto que os produtos do fruto têm aplicação comercial. Este trabalho teve como objetivo a extração de bromelina a partir de cascas de abacaxi através de sistema de duas fases aquosas (SDFA), e sua aplicação em hidrogel polimérico. Foram realizados estudos de estabilidade da bromelina comercial, em que se observou maior estabilidade em pH 5,0 com menor perda da atividade relativa em todas as temperaturas estudadas (20, 30, 40 e 50°C). O estudo da extração da bromelina em SDFA formado por polietileno glicol (PEG) e ácido poliacrílico (PAA) (com auxílio da análise de variância de parâmetros como rendimento, fator de purificação e coeficiente de partição) proporcionou rendimento de 335% e fator de purificação de 25,8. Os hidrogéis poliméricos à base de PEG estudados apresentaram-se flexíveis, com pouca elasticidade e taxa de absorção superior a 1000%. Hidrogel carreado de bromelina pelo método de turgescência proporcionou a maior liberação da enzima, assim como a maior atividade (80% da bromelina liberada em 24 h e 278 ± 89 U/mL)
Bromelain is a collective name for the proteolytic enzymes found in the stem, fruit and leaves of pineapple (Ananas comosus Merr.). Bromelain possesses anti-inflammatory properties, debridement, among others. For bromelain production one should preferably use the waste materials, whereas pineapple fruit products have commercial application. This study aimed to extract bromelain from pineapple peels using aqueous two-phase system (ATPS), and its application in polymeric hydrogels. Stability studies of commercial bromelain were performed, which found greater stability at pH 5.0 with minor loss of relative activity at all temperatures studied. The study of bromelain extraction in ATPS composed by polyethylene glycol (PEG) and poly acrylic acid (PAA) (with assistance of variance analysis of parameters such as yield, purification factor and partition coefficient) showed yield 335% and purification factor of 25.8. The PEG-based hydrogels studied presented flexibility, low elasticity and swelling ratio higher than 1000%. Hydrogel containing bromelain, loading by embedding (solvent sorption) method, yielded the highest enzyme release, as well as the highest activity (80% bromelain released over 24 h and 278 ± 89 U / mL)
Subject(s)
Bromelains/pharmacology , Hydrogel, Polyethylene Glycol Dimethacrylate/pharmacology , Ananas/anatomy & histology , Biotechnology , Technology, PharmaceuticalABSTRACT
In this work, the thermodynamic equilibrium and applying of PEG4000/Phosphate ATPS on the purification of bromelain extracted from pineapple was studied. A rigorous study of the equilibrium curves and tie-line length from PEG4000/phosphate ATPS were done for the pH 6-11 at 25ºC. Results showed that there was augment in the PEG and salt contents with the high pH value from PEG4000/Phosphate ATPS and two-phase formation needed only increasing the PEG content. Two tie-line length at pH 11 from PEG4000/Phosphate ATPS were optimal condition for bromelain purification, one on composition of 14 percent PEG and 13 percent salt and other at 12.6 percent PEG and 12.2 percent salt, while a 25-62 folds of enzyme was found. SDS-PAGE electrophoreses had one band only, which showed that bromelain was purified. Optimum conditions of bromelain use were found at pH 7 and between 30-40ºC.
ABSTRACT
This work aimed to establish the relationship between the compositions and pH of ATPS PEG 6000/CaCl2 and the proteins partition from maize malt and also to simplify the process optimization in ATPS for a statistical model, established by response surface methodology (RSM). Results showed that these were no influence of pH on the phase diagrams and on the composition of tie line length of PEG 6000/CaCl2 ATPS. SRM analyses showed that elevated pH and larger tie line length were the best conditions for recovering of maize malt proteins. The maximum partition coefficient by PEG 6000/CaCl2 ATPS was about 4.2 and was achieved in ATPS in a single purification step. The theoretical maximum partition coefficient was between 4.1-4.3. The process was very suitable for continuous aqueous two-phase purification due to the stability of proteins (e.g. and -amylases) and could increase their content into middle.
Este trabalho objetivou encontrar uma relação entre a composição e o pH do sistema bifásico aquoso (SBA) PEG 6000/CaCl2 e a partição de proteínas do malte de milho, e assim simplificando a otimização do processo por um modelo estatístico, estabelecido por metodologia de superfície de resposta (RSM). Os resultados mostraram que não houve influência do pH sobre os diagramas de fases e sobre a composição das linhas de amarração do SBA PEG/CaCl2. As analises RSM mostraram que em pH elevado e nas maiores linha de amarração encontra-se a melhor condição para a recuperação das proteínas do malte de milho. O coeficiente de partição máximo foi cerca de 4,2 para uma única etapa de purificação no SBA 6000/CaCl2. O coeficiente de partição máximo encontrado teoricamente esteve entre 4,1-4,3. O processo é adequado para a purificação contínua via sistemas bifásicos aquosos, já que as proteínas do malte (ex: e -amilases) são estáveis e podendo elevar sua concentração no meio.
ABSTRACT
Immobilized penicillin acylase was used for bioconversion of penicillin G into 6-APA in aqueous two-phase systems consisted of a light-sensitive polymer PNBC and a pH-sensitive polymer PADB.Partition coefficients of 6-APA was found to be:about 5.78,in the presence of 1% NaCl.Enzyme kinetic showed that reaction reached equilibrium at 7h or so.The 6-APA mole yields were 85.3%(pH 7.8,and 20 ℃) and this value was about 20%higher than control in reaction of single aqueous phase buffer.Partition coefficient of penicillin G(Na) washardly changeable,while partition coefficient of product,6-APA and phenylacetate acid was significantly changeable.Reason is due to Donnan effect of phase systems andhydrophobicity of products.The change of partition coefficients of products also affects bioconversion yield of products.In the aqueous two-phase systems,substrate,penicillin G,products 6-APA and phenylacetate acid are biased in top phase,while immobilized penicillin acylase is completely partitioned in bottom.Substrate,penicillin G enters into bottom phase,and it is catalyzed into 6-APA and phenylacetate acid,then the products enter into top phase.Finally,inhibition of substrate and products is removed to result in improvement of products yield.Moreover,immobilized enzymehashigher efficiency than immobilized cells and occupy smaller volume.Comparing with free enzyme,immobilized enzymehashigher stability,longer use life,completely partitioned in bottom phase and recycle.Bioconversion in two-phase systems using immobilized penicillin acylase showed outstanding advantage.The light-sensitive copolymer forming aqueous two-phase systems could be recovered by laser radiation at 488 nm or filtrated 450 nm light,while pH-sensitive polymer PADB could be recovered by isoelectric point(pH 4.1).The recovery of the two copolymers was 95%~99%.