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Pediococcus pentosaceus was cultivated in MRS medium supplemented or not with polydextrose under different conditions in order to evaluate its effect on cell growth, lactic acid and bacteriocin-like inhibitory substance (BLIS) production. Independent variables were pH (4.0, 5.0, 6.0), rotational speed (50, 100, 150 rpm), polydextrose concentration (0.5, 1.0, 1.5%) and temperature (25, 30, 35 °C), while cell concentration and productivity after 24 h, maximum specific growth rate, specific rate of substrate (glucose) consumption, volumetric and specific lactic acid productivities, yields of biomass and lactic acid on consumed substrate were the dependent. The maximum cell concentration (10.24 ± 0.16 gX L-1) and productivity (0.42 ± 0.01 gX L-1 h-1) were achieved at pH 6.0, 35 °C, 150 rpm using 1.5% polydextrose, while the maximum specific growth rate (0.99 ± 0.01 h-1) and yield of biomass (2.96 ± 0.34 gX gS-1) were achieved at the same pH and polydextrose concentration, but at 25 °C and 50 rpm. The specific substrate consumption rate (0.09 ± 0.02 gS gX-1 h-1) and the volumetric lactic acid productivity (0.44 ± 0.02 gP L-1 h-1) were maximized at pH 6.0, 35 °C, 50 rpm and 0.5% polydextrose. BLIS produced in this last run displayed the highest antibacterial activity against Escherichia coli, while the same activity was displayed against Enterococcus faecium using 1.5% polydextrose. These results appear to be quite promising in view of possible production of this BLIS as an antibacterial agent in the food industry.

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L-asparaginase II (ASNase) is the biopharmaceutical of choice for the treatment of acute lymphoblastic leukaemia. In this study, E. coli BL21 (DE3) transformed with the pET15b + asnB vector which expresses recombinant ASNase was used as a source to obtain this enzyme. The ideal conditions to produce ASNase would be a high level of secretion into the extracellular medium, which depends not only on the application of molecular biology techniques but also on the development of a strategy to modify cell permeability such as the addition of substances to the culture medium that stimulate destabilisation of structural components of the cell. Thus, the growth of E. coli BL21 (DE3) in modified Luria-Bertani broth, supplemented with 0.8% (w/v) glycine and 6% (v/v) n-dodecane, increased the total yield of ASNase by about 50% (15,108 IU L-1) and resulted in a 16-fold increase in extracellular enzymatic productivity (484 IU L-1 h-1), compared to production using the same medium without addition of these substances. Most of the enzyme (89%) was secreted into the culture medium 24 h after the induction step. This proposed approach presents a simple strategy to increase extracellular production of ASNase in E. coli.

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The efficacy of a simple laboratory method for cell disruption based on the glass bead stirring, sonication, osmotic shock, freezing and grinding, or use of solvents and detergents was assessed in this study, via measurements of the release of total protein and L-asparaginase activity. Three different microbial sources of L-asparaginase were used: Escherichia coli BL21 (DE3), Leucosporidium muscorum, and Aspergillus terreus (CCT 7693). This study adjusted and identified the best procedure for each kind of microorganism. Sonication and glass bead stirring led to obtaining filamentous fungus cell-free extracts containing high concentrations of soluble proteins and specific activity; however, sonication was the best since it obtained 4.61 ± 0.12 IU mg-1 after 3 min of operation time. Mechanical methods were also the most effective for yeast cell disruption, but sonication was the technique which yielded a higher efficiency releasing 7.3 IUtotal compared to glass bead stirring releasing 2.7 IUtotal at the same operation time. For bacterium, sonication proved to be the best procedure due to getting the highest specific activity (9.01 IU mg-1) and total enzyme activity (61.7 IU). The data presented lead to conclude that the mechanical methods appeared to be the most effective for the disintegration of the all microbial cells studies. This is the first report related to the experimental comparison of L-ASNase extraction procedures from different microorganisms, which can also be used for extracting periplasm located enzymes from other organisms.

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Probiotics have gained increasing attention due to several health benefits related to the human digestive and immune systems. Pediococcus spp. are lactic acid bacteria (LAB) that are widely described as probiotics and characterized as coccus-shaped bacteria (arranged in tetrads), Gram-positive, non-motile, non-spore forming, catalase-negative, and facultative anaerobes. There are many Pediococcus strains that produce pediocin, an effective antilisterial bacteriocin. Pediocins are small, cationic molecules consisting of a conserved hydrophilic N-terminal portion containing the YGNGV motif and an amphiphilic or hydrophobic C-terminal variable portion. A number of studies have been developed with Pediococcus isolated from multiple biological niches to conduct fermentation processes for pediocin or Pediococcus cell production. This review gathers the most significant information about the cultivation, mode of action, and variability of bacteriocins produced by Pediococcus spp., emphasizing their applications in the areas of food and clinical practice. This updated panorama assists in delimiting the challenges that still need to be overcome for pediocin use to be approved for human consumption and the food industry.

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Chemical preservatives have been traditionally used during the manufacturing of processed products. However, the continuous growing interest of consumers for fresh and natural products makes it necessary to search for alternative compounds. In this context, food industries have been widely using lactic acid bacteria (LAB) as natural preservatives, due to their ability to produce antibacterial compounds such as bacteriocins. Similarly, pharmaceutical industries have improved the use of these bacterial peptides, with antibacterial activity, trying to reduce the indiscriminate use of antibiotics in food products for human and animal consumption. Among LAB, Lactobacillus plantarum can be adapted to various niches thanks to its ability to ferment a wide range of carbohydrates. Additionally, it can be used as starter culture in food fermentations and as an ingredient for probiotic foods, contributing to the organoleptic characteristics of foods at the same time prolonging the shelf-life and safety of these products. The amount of valuable substances obtained from L. plantarum species isolated from different ecological niches is also worth noting, thus proving it to be one of the most important and versatile species among LAB.

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Sucrose hydrolysis by invertase [EC.3.2.1.26] produces inverted sugar syrup, an ingredient mainly used in the food industry. To properly catalyze hydrolysis, the enzyme should be reused after this reaction. It is advisable to maintain constant activity over a considerable period. Thus, sucrose hydrolysis was performed in a membrane bioreactor - a continuously stirred tank reactor coupled with an ultrafiltration membrane (UFM) which provides good diffusion and high activity per unit volume. Molecular weight cut-off for soluble invertase UFMs was up to 100kDa. This study focused on the role of UFM invertase cut-off as it is the main element in the process. We demonstrated that both the cut-off and chemical nature of the UFM affected specific invertase activity.

A hidrólise da sacarose através da invertase [EC.3.2.1.26] gera xarope de açúcar invertido, que é usado principalmente como ingrediente na indústria alimentícia. Para ter-se uma hidrólise satisfatória, a enzima deve ser reaproveitada após a reação. É desejável que sua atividade seja mantida constante durante um período considerável de reação. A hidrólise da sacarose foi realizada em um reator com membrana (RM) - que é um reator continuamente agitado acoplado a uma membrana de ultrafiltração (MUF) -, porque apresenta efeitos mínimos de difusão e elevada atividade por unidade de volume. O corte molecular da MUF utilizada para reter a invertase solúvel dentro do MR foi de até 100kDa. Como a invertase é o elemento principal deste processo, este trabalho foi focado no papel do corte molecular da MUF na sua atividade. O corte molecular e a natureza química da membrana-UF mostraram afetar a atividade específica da invertase.

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Multienzymatic conversion of sucrose into fructose and gluconic acid was studied through fed-batch and continuous (in a membrane reactor) processes. The law of substrate addition (sucrose or glucose) for the fed-batch process which led to a yield superior to 80% was the decreasing linear type, whose feeding rate (ϕ; L/h) was calculated through the equation: ϕ = ϕ(o) - k.t, where ϕ(o) (initial feeding rate, L/h), k (linear addition constant, L/h (2)), and t (reaction time, h). In the continuous process, the yield of conversion of sucrose (Y) was superior to 70% under the following conditions: dilution rate = 0.33 h(-1), total duration of 15 h, pH 5.0, 37 °C and initial sucrose concentration of 64 g/L (Y = 92%), 100 g/L (Y = 83%), or 150 g/L (Y = 76%).

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Conversion of sucrose into fructose and gluconic acid using invertase, glucose oxidase and catalase was studied by discontinuous (sequential or simultaneous addition of the enzymes) and continuous (simultaneous addition of the enzymes in a 100 kDa-ultrafiltration membrane reactor) processes. The following parameters were varied: concentration of enzymes, initial concentration of substrates (sucrose and glucose), pH, temperature and feeding rate (for continuous process). The highest yield of conversion (100 percent) was attained through the discontinuous (batch) process carried out at pH 4.5 and 37 ºC by the sequential addition of invertase (14.3 U), glucose oxidase (10,000 U) and catalase (59,000 U).

Neste trabalho estudou-se a conversão da sacarose em frutose e ácido glicônico, usando as enzimas invertase, glicose oxidase e catalase, através do emprego de processo descontínuo (com adição sequencial ou simultânea das enzimas) e contínuo (adição simultânea das enzimas em reator com membrana acoplado à membrana de ultrafiltração de 100 kDa). Os parâmetros variados foram: a concentração das enzimas, a concentração inicial dos substratos (sacarose e glicose), o pH, a temperatura e a vazão específica de alimentação (processo contínuo). Obteve-se rendimento de 100 por cento, quando a conversão foi conduzida por processo descontínuo em pH 4,5 e a 37 ºC com adição seqüencial das enzimas invertase (14,3 U), glicose oxidase (10.000 U) e catalase (59.000 U).

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Invertase, whether adsorbed on styrene-divinylbenzene copolymers or otherwise, was used for continuous sucrose hydrolysis using a cell-type membrane reactor (CTMR), coupled with an ultra (UF-100kDa), or a microfiltration (MF- pore diameter of 5 µm) membrane. In all tests, the pH (5.5), temperature (30 ºC), reaction volume (10 mL) and agitation (100 rpm) were set constant; whereas, variable parameters were: feeding rate (0.4, 0.8 and 1.6 h-1), inlet sucrose concentration (2.5, 6.5, 50 and 100 mM) and enzyme/resin ratio (1.64 mg or 3.28 mg of protein per 25, 50 or 100 mg of resin). The best result (yield of 100 percent, steady-state duration over 20h and specific reaction rate over 243 x 10-3 mmol/h.mE) was obtained when insoluble invertase (1.64 mg protein/100 mg resin) was used to convert 50 mM or 100 mM of sucrose solution at 0.4 h-1 using a UF-CTMR.

Invertase, na forma adsorvida ou não em copolímeros de estireno-divinilbenzeno, foi usada para a hidrólise contínua de sacarose utilizando um reator com membrana (RM), acoplado a uma membrana de ultrafiltração (UF-100kDa), ou de microfiltração (MF - um diâmetro de poro de 5µm). Em todos os testes, o pH (5,5), a temperatura (30ºC), o volume reacional (10mL) e a agitação (100 rpm) foram mantidas constantes; os parâmetros variados foram: a vazão de alimentação (0,4; 0,8 e 1,6 h-1), a concentração de sacarose alimentada (2,5; 6,5; 50 e 100 mM) e a relação enzima/resina (1,64 mg ou 3,28 mg de proteína por 25, 50 ou 100 mg de resina). O melhor resultado (um rendimento de 100 por cento, um período de estado estacionário acima de 20h e uma taxa de reação específica maior de 243 x 10-3 mmol/h.mE) foi obtido quando a invertase insolúvel (1,64 mg de proteína/100 de mg resina) foi usado para converter 50 mM ou 100 mM de solução de sacarose a 0,4 h-1 usando UF-RM.

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The enzymatic bioconversion of xylose into xylitol by xylose reductase (XR) is an alternative for chemical and microbiological processes. The partial purified XR was obtained by using the following three procedures: an agarose column, a membrane reactor or an Amicon Ultra-15 50K Centrifugal Filter device at yields of 40 percent, 7 percent and 67 percent, respectively.

A bioconversão enzimática da xilose em xilitol pela xilose redutase (XR) é uma alternativa para as vias química e microbiológica. Avaliouse a purificação parcial da XR, utilizando os três seguintes procedimentos: uma coluna de agarose, um reator com membrana ou tubos de ultracentrifugação Amicon Ultra-15 50K, com rendimento de 40 por cento, 7 por cento ou 67 por cento, respectivamente.

RESUMEN

The enzymatic bioconversion of xylose into xylitol by xylose reductase (XR) is an alternative for chemical and microbiological processes. The partial purified XR was obtained by using the following three procedures: an agarose column, a membrane reactor or an Amicon Ultra-15 50K Centrifugal Filter device at yields of 40%, 7% and 67%, respectively.

RESUMEN

The enzymatic bioconversion of xylose into xylitol by xylose reductase (XR) is an alternative for chemical and microbiological processes. The partial purified XR was obtained by using the following three procedures: an agarose column, a membrane reactor or an Amicon Ultra-15 50K Centrifugal Filter device at yields of 40%, 7% and 67%, respectively.

A bioconversão enzimática da xilose em xilitol pela xilose redutase (XR) é uma alternativa para as vias química e microbiológica. Avaliouse a purificação parcial da XR, utilizando os três seguintes procedimentos: uma coluna de agarose, um reator com membrana ou tubos de ultracentrifugação Amicon Ultra-15 50K, com rendimento de 40%, 7% ou 67%, respectivamente.

RESUMEN

Glucose-6-phosphate dehydrogenase (G6PDH) is an important enzyme used in biochemical and medical studies and in several analytical methods that have industrial and commercial application. This work evaluated the extraction of G6PDH in aqueous two-phase system (ATPS) of poly(ethyleneglycol) (PEG)/phosphate buffer, using as enzyme source a medium prepared through commercial baker's yeast disruption. Firstly, the effects of PEG molar mass on the enzyme partition and of homogenization and rest on the system equilibrium were investigated. Afterwards, several ATPS were prepared using statistical analysis (2² factorial design). The results, including kinetic and thermodynamic parameters for the G6PDH activity, showed partial purification of this enzyme in ATPS composed of 17.5 percent (w/w) PEG400 and 15.0 percent (w/w) phosphate. A high enzymatic recovery value (97.7 percent), a high partition coefficient (351), and an acceptable purification factor (2.28 times higher than in cell homogenate) were attained from the top phase. So, it was possible to attain an effective enzyme pre-purification by separating some contaminants with a simple method such as liquid-liquid extraction in aqueous two-phase systems (ATPS).

Glicose-6-fosfato desidrogenase (G6PDH) é uma importante enzima usada em estudos bioquímicos e médicos, bem como em diversos métodos analíticos com aplicação comercial e industrial. Neste trabalho foi avaliado a extração da G6PDH em sistemas de duas fases aquosas (ATPS) constituídos por poli(etilenoglicol) (PEG)/tampão fosfato, usando como fonte de enzima um meio preparado por rompimento de leveduras de panificação comercial. Inicialmente foram investigados os efeitos da massa molar do PEG na partição da enzima e da homogeneização e repouso no equilíbrio do sistema. Na sequência, diversos ATPS foram preparados usando análise estatística (planejamento fatorial 2²). Os resultados, incluindo parâmetros cinéticos e termodinâmicos para a atividade da G6PDH, indicaram parcial purificação desta enzima em ATPS constituídos por 17,5 por cento (p/p) PEG400 e 15,0 por cento (p/p) fosfato. Um alto valor de recuperação enzimática (97,7 por cento), um alto coeficiente de partição (351), e um fator de purificação aceitável (2,28 vezes maior que em homogenato celular) foram obtidos na fase superior do sistema. Assim, foi possível alcançar uma pré-purificação eficaz da enzima separando alguns contaminadores aplicando um método simples tal como a extração líquido-líquido em sistemas bifásicos (ATPS).

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This article aims at the evaluation of the catalytic performance of glucose oxidase (GO) (EC.1.1.3.4) for the glucose/gluconic acid conversion in the ultrafiltration cell type membrane reactor (MB-CSTR). The reactor was coupled with a Millipore ultrafiltration-membrane (cutoff of 100 kDa) and operated for 24 h under agitation of 100 rpm, pH 5.5, and 30 degrees C. The experimental conditions varied were the glucose concentration (2.5, 5.0, 10.0, 20.0, and 40.0 mM), the feeding rate (0.5, 1.0, 3.0, and 6.0/h), dissolved oxygen (8.0 and 16.0 mg/L), GO concentration (2.5, 5.0, 10.0, and 20.0 U(GO)/mL), and the glucose oxidase/catalase activity ratio (U(GO)/U(CAT))(1:0, 1:10, 1:20, and 1:30). A conversion yield of 80% and specific reaction rate of 40 x 10(-4) mmol/h x U(GO) were attained when the process was carried out under the following conditions: D =3.0/h, dissolved oxygen =16.0 mg/L, [G] =40 mM, and (U(GO)/U(CAT)) =1:20. A simplified model for explaining the inhibition of GO activity by hydrogen peroxide, formed during the glucose/gluconic acid conversion, was presented.

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The strain Saccharomyces cerevisiae W303-181, having the plasmid YEpPGK-G6P (built by coupling the vector YEPLAC 181 with the promoter phosphoglycerate kinase 1), was cultured by fed-batch process in order to evaluate its capability in the formation of glucose 6-phosphate dehydrogenase (EC.1.1.1.49). Two liters of culture medium (10.0 g/L glucose, 3.7 g/L yeast nitrogen broth (YNB), 0.02 g/L L-tryptophan, 0.02 g/L L-histidine, 0.02 g/L uracil, and 0.02 g/L adenine) were inoculated with 1.5 g dry cell/L and left fermenting in the batch mode at pH 5.7, aeration of 2.2 vvm, 30 degrees C, and agitation of 400 rpm. After glucose concentration in the medium was lower than 1.0 g/L, the cell culture was fed with a solution of glucose (10.0 g/L) or micronutrients (L-tryptophan, L-histidine, uracil, and adenine each one at a concentration of 0.02 g/L) following the constant, linear, or exponential mode. The volume of the culture medium in the fed-batch process was varied from 2 L up to 3 L during 5 h. The highest glucose 6-phosphate dehydrogenase activity (350 U/L; 1 U=1 micromol of NADP/min) occurred when the glucose solution was fed into the fermenter through the decreasing linear mode.

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Glucose-6-phosphate dehydrogenase (G6PDH) is an important enzyme used in biochemical and medical studies and in several analytical methods that have industrial and commercial application. This work evaluated the extraction of G6PDH in aqueous two-phase system (ATPS) of poly(ethyleneglycol) (PEG)/phosphate buffer, using as enzyme source a medium prepared through commercial baker's yeast disruption. Firstly, the effects of PEG molar mass on the enzyme partition and of homogenization and rest on the system equilibrium were investigated. Afterwards, several ATPS were prepared using statistical analysis (2² factorial design). The results, including kinetic and thermodynamic parameters for the G6PDH activity, showed partial purification of this enzyme in ATPS composed of 17.5% (w/w) PEG400 and 15.0% (w/w) phosphate. A high enzymatic recovery value (97.7%), a high partition coefficient (351), and an acceptable purification factor (2.28 times higher than in cell homogenate) were attained from the top phase. So, it was possible to attain an effective enzyme pre-purification by separating some contaminants with a simple method such as liquid-liquid extraction in aqueous two-phase systems (ATPS).

Glicose-6-fosfato desidrogenase (G6PDH) é uma importante enzima usada em estudos bioquímicos e médicos, bem como em diversos métodos analíticos com aplicação comercial e industrial. Neste trabalho foi avaliado a extração da G6PDH em sistemas de duas fases aquosas (ATPS) constituídos por poli(etilenoglicol) (PEG)/tampão fosfato, usando como fonte de enzima um meio preparado por rompimento de leveduras de panificação comercial. Inicialmente foram investigados os efeitos da massa molar do PEG na partição da enzima e da homogeneização e repouso no equilíbrio do sistema. Na sequência, diversos ATPS foram preparados usando análise estatística (planejamento fatorial 2²). Os resultados, incluindo parâmetros cinéticos e termodinâmicos para a atividade da G6PDH, indicaram parcial purificação desta enzima em ATPS constituídos por 17,5% (p/p) PEG400 e 15,0% (p/p) fosfato. Um alto valor de recuperação enzimática (97,7%), um alto coeficiente de partição (351), e um fator de purificação aceitável (2,28 vezes maior que em homogenato celular) foram obtidos na fase superior do sistema. Assim, foi possível alcançar uma pré-purificação eficaz da enzima separando alguns contaminadores aplicando um método simples tal como a extração líquido-líquido em sistemas bifásicos (ATPS).

RESUMEN

The conversion of glucose and fructose into gluconic acid (GA) and sorbitol (SOR) was conducted in a batch reactor with free (CTAB-treated or not) or immobilized cells of Zymomonas mobilis. High yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/L (glucose plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 U/L. The concentration of the products varied hyperbolically with time according to the equations (GA) = t (GA)max /(W(GA) + t), (SOR) = t (SOR)max/(W(SOR) + t), V(GA) = [W(GA) (GA)max]/(W(GA) + t)2 and V(SOR) = [W(SOR) (SOR)max]/(W(SOR) + t)2. Taking the test carried out with free CTAB-treated cells as an example, the constant parameters were (GA)max = 541 g/L, (SOR)max = 552 g/L, WGA = 4.8 h, W(SOR) = 4.9 h, v(GA) = 112.7 g/L x h and v(SOR) = 112.7 g/L x h.

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Xylosereductase (XR) (E.C.1.1.1.21), produced by Candida guilliermondii, grown in sugar cane bagasse hydrolysate, was separated directly from the cell homogenate by reversed micelles of cetyl trimethyl ammonium bromide (CTAB), attaining a recovery yield of 100% and enrichment factor of 5.6 fold. The extraction conditions were: pH=7.0, electrical conductivity= 14 mS/cm, T=5 degrees C, 5% (w/w) of hexanol, 22% (w/w) of butanol and 0.15 M CTAB. The XR after extraction was stable in pH interval of 6.0-6.5 and its heat inactivation constant was about 6.5 fold higher than that before extraction. The 'V IND. max' values against both xylose and NADPH for XR before and after extraction by reversed-micelles differed about 6%, whereas the difference on KM values were more pronounced. The ('K IND. m') 'IND. xylose' for XR after extraction was about 35% higher than before extraction, meanwhile ('K IND. m') 'IND. NADPH' was about 30% lower after than before extraction. As the KM variations indirectly signaled, the XR affinity simultaneously diminishes for xylose and increases for NADPH. This could probably explain why the 'V IND. max' values for XR before and after extraction were quite similar

A xilose redutase (XR) (E.C.1.1.1.21), produzida por Candida guilliermondii cultivada em hidrolisado de bagaço de cana de açúcar, foi separada diretamente do homogenato livre de células através da técnica de micelas reversas feitas com cetil trimetil brometo de amônio (CTAB). Obteve-se um rendimento de recuperação da enzima de 100% e um fator de enriquecimento de 5,6 vezes. As condições de extração foram: pH=7,0, condutividade elétrica = 14 mS/cm, T= 5 ºC, 5% (w/w) de hexanol, 22% (w/w) de butanol e 0.15M CTAB. A XR após a extração manteve-se estável no intervalo de pH entre 6.0 e 6.5, sendo a constante de inativação térmica cerca de 6,5 vezes maior do que aquela antes da extração. Os valores de Vmax da XR frente à xilose e NADPH antes e após a extração por micelas reversas diferiram cerca de 6%, enquanto que as diferenças nos valores de KM foram mais pronunciadas. O (KM)xilose para a XR após a extração foi cerca de 35% maior do que antes da extração, enquanto que (KM)NADPH foi 30% menor após do que antes da extração. As variações nos valores de KM indicam, indiretamente, que a afinidade da XR simultaneamente diminui para a xilose e aumenta para o NADPH. Este resultado poderia explicar a razão pela qual os valores de Vmax antes e após a extração terem sido praticamente iguais

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This communication describes a method for adsorbing the invertase (EC.3.2.1.26) on DOWEX'registred mark' anion exchange resin. Among the types of DOWEX'registred mark' resins studied (1x8:50-400; 1x4:50-400 and 1x2:100-400), 1X4-200 was the most suitable, because it adsorbed the invertase molecules completely and the complex 1X4-200/invertase retained 100% of the catalytic activity. Moreover, no leakage of enzyme from the support was noted at the end of the sucrose hydrolysis

O presente trabalho descreve um método de adsorção da invertase (EC. 3.2.1.26) na resina de troca aniônica do tipo Dowex®. Entre os tipos de resinas Dowex® estudados (1x8:50-400; 1x4:50-400 e 1x2:100-400), 1x4-200 foi a mais apropriada devido à completa adsorção das moléculas de invertase e a sua retenção de atividade catalítica de 100% do complexo 1x4-200/invertase. Salienta-se ainda a ausência do desprendimento da enzima do suporte após o término da hidrólise da sacarose

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The conversion of glucose and fructose into gluconic acid (GA) and sorbitol (SOR) was conducted in a batch reactor with free (CTAB-treated or not) or immobilized cells of Zymomonas mobilis. High yields (more than 90%) of gluconic acid and sorbitol were attained at initial substrate concentration of 600 g/L (glucose plus fructose at 1:1 ratio), using cells with glucose-fructose-oxidoreductase activity of 75 U/L. The concentration of the products varied hyperbolically with time according to the equations (GA)=t(GA)(max)/(W(GA) +t), (SOR)=t (SOR)(max)/(W(Sor)+t), v(GA)=[W(GA) (GA)(max)]/(W(GA)+t)(2) and V(SOR)=[W(SOR) (SOR)(max)]/(W(SOR)+t)(2). Taking the test carried out with free CTAB-treated cells as an example, the constant parameters were (GA)(max)= 541 g/L, (SOR)(max)=552 g/L, W(GA)=4.8h, W(SOR)=4.9h, upsilon(GA)=112.7 g/L. and upsilon(SOR)=112.7 g/L.

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