Photochemical & Photobiological Sciences, 2018
Zn(ii)meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin was applied in the photodynamic inactivation... more Zn(ii)meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin was applied in the photodynamic inactivation ofLeishmania braziliensis, leading to considerable cell damage.
International journal of biological macromolecules, Jan 25, 2018
Incorporating enzymes into calcium alginate beads is an effective method to immobilise them and t... more Incorporating enzymes into calcium alginate beads is an effective method to immobilise them and to preserve, at the same time, their catalytic activity. Sodium alginate was mixed with Aspergillus ficuum tannase in aqueous solution, and tannase-loaded calcium alginate beads were prepared using a simple droplet-based microfluidic system. Extensive experimental analysis was carried out to characterise the samples. Microscopic imaging revealed morphological differences between the surfaces of bare alginate matrix and tannase-loaded alginate beads. Thermal analysis allowed assessing the hydration contents of alginate and revealed the presence of tannase entrapped in the loaded beads, which was also confirmed by vibrational spectroscopy. X-ray diffraction allowed us to conclude that alginate of tannase-loaded beads is not crystalline, which would make them suitable as carriers for possible controlled release. Moreover, they could be used in food applications to improve tea quality or clar...
Patients with acute schistosomiasis were studied before and after oxamniquine treatment. They had... more Patients with acute schistosomiasis were studied before and after oxamniquine treatment. They had been exposed to cercariae 5 to 9 weeks before, and presented compatible clinical manifestations, eosinophilia, and high levels of total IgE. Interferon-γ (IFN-γ) and interleukin-4 were measured by ELISA in whole blood samples under soluble egg antigen or soluble adult worm preparation stimulation. After treatment, the reduction of leukocytosis and eosinophilia were not significant, but total IgE levels decreased significantly, in contrast to IFN-γ levels that were significantly increased. The oxamniquine treatment of acute schistosomiasis patients is followed by an improvement of a Th1 response in vitro. If this response has a protective aspect is unknown, and some investigations need to be realized.
This work proposes a simple, cost-effective, and efficient preparation of a composite made from m... more This work proposes a simple, cost-effective, and efficient preparation of a composite made from magnetic diatomaceous earth (mDE) coated with polyaniline (mDE@PANI). The material was used as a matrix for immobilizing industrial enzymes: invertase, β-galactosidase, and trypsin. The mDE@PANI was characterized by several methods, and the results suggested that the nanoparticles were approximately 12 nm in size, exhibited superparamagnetic behavior, and displayed a good magnetic response and that magnetite comprised the main iron oxide phase. Moreover, several studies were conducted for all immobilized derivatives, including determination of optimal pH and temperature; kinetic parameters; thermal stability and reusability. The obtainment of three novel magnetic biocatalysts with superior performance (in terms of activity and stability) compared to their free counterparts demonstrated the efficacy of the mDE@PANI nanoparticles. In addition, the enzymatic derivatives can be easily recovered from the reactor by using an external magnetic field. Finally, the present methodology allowed the achievement of good mDE@PANI matrix together with three promising magnetic biocatalysts with several potential biotechnological applications.
Anais do XX Congresso Brasileiro de Engenharia Química, 2015
Peptides with bioactive properties can be released from the precursor proteins during food proces... more Peptides with bioactive properties can be released from the precursor proteins during food processing or digestion, and act as antioxidative compounds. Although, it has been proven that hydrolysate exerts higher antioxidant activity than purified peptides. The process of enzyme immobilization proved to be more practical and advantageous for catalysis than using free enzyme. The aim of this study was to use a protease produced by Penicillium aurantiogriseum immobilized on polianilin-coated magnetic nanoparticles, for bovine casein hydrolysis and to evaluate the hydrolysate antioxidant properties. The 60-80% saline fraction of crude extract was used in immobilization. Commercial casein from bovine milk 1% (w/v) was hydrolyzed by 10 mg/mL of immobilized protease. The casein hydrolysates were used in ABTS and H 2 O 2 scavenging activity assays, where Trolox was used as standard. In the ABTS scavenging assay, the hydrolysate (1% w/v) revealed a 1341 µmol of Trolox equivalent activity and in the hydrogen peroxide scavenging assay, the hydrolysate (using 0.1% w/v) presented a 547.82 µmol of Trolox equivalent activity. In both assays the hydrolysates presented a more than 2.5 times greater activity than non-hydrolyzed casein, which validates the process capacity of developing casein derived natural antioxidant ingredients with potential for functional foods.
To investigate the effect of ions on brain acetylcholinesterase (AChE; EC 3.1.1.7) activities fro... more To investigate the effect of ions on brain acetylcholinesterase (AChE; EC 3.1.1.7) activities from economic important fish [pirarucu, Arapaima gigas; tambaqui, Colossoma macropomum; cobia, Rachycentron canadum (R. canadum) and Nile tilapia, Oreochromis niloticus (O. niloticus)] comparing with a commercial enzyme from electric eel [Electrophorus electricus (E. electricus)]. Methods: The in vitro exposure was performed at concentrations ranging from 0.001 to 10 mmol/L (except for ethylene diamine tetraacetic acid; up to 150 mmol/L). Inhibition kinetics on R. canadum and O. niloticus were also observed through four methods (Michaelis-Menten, Lineweaver-Burk, Dixon and Cornish-Bowden plots) in order to investigate the type of inhibition produced by some ions. Results: Hg 2+ , As 3+ , Cu 2+ , Zn 2+ , Cd 2+ caused inhibition in all the species under study. Ca 2+ , Mg 2+ and Mn 2+ induced slight activation in R. canadum enzyme while Pb 2+ , Ba 2+ , Fe 2+ , Li + inhibited the AChE from some of the analyzed species. The lowest IC 50 and Ki values were estimated for E. electricus AChE in presence of Hg 2+ , Pb 2+ , Zn 2+. Under our experimental conditions, the results for R. canadum and O. niloticus, As 3+ , Cu 2+ , Cd 2+ , Pb 2+ and Zn 2+ showed a noncompetitive/mixed-type inhibition, while Hg 2+ inhibited the enzyme in a mixed/competitivelike manner. Conclusions: E. electricus AChE activity was affected by ten of fifteen ions under study showing that this enzyme could undergo interference by these ions when used as pesticide biosensor in environmental analysis. This hindrance would be less relevant for the crude extracts.
Brazilian Journal of Medical and Biological Research, 2011
The antischistosomal activity of the sulfated polysaccharide α-D-glucan (Glu.SO 4) extracted from... more The antischistosomal activity of the sulfated polysaccharide α-D-glucan (Glu.SO 4) extracted from Ramalina celastri was evaluated after encapsulation into liposomes (Glu.SO 4-LIPO) in Schistosoma mansoni-infected mice. The effect of treatment with Glu.SO 4 and Glu.SO 4-LIPO (10 mg/kg) on egg elimination, worm burden and hepatic granuloma formation was assessed using female albino Swiss mice, 35-40 days of age, weighing 25 ± 2 g, infected with 150 cercariae/animal (Biomphalaria glabrata, BH strain). Four groups (N = 10) were studied, two controls (empty liposomes and NaCl) and two treated groups (Glu.SO 4-LIPO and Glu.SO 4) using a single dose. Parasitological analysis revealed that Glu.SO 4-LIPO was as efficient as Glu.SO 4 in reducing egg elimination and worm burden. Treatment with free Glu.SO 4 and Glu.SO 4-LIPO induced a statistically significant reduction in the number of granulomas (62 and 63%, respectively). Lectin histochemistry showed that wheat germ agglutinin intensely stained the egg-granuloma system in all treated groups. On the other hand, peanut agglutinin stained cells in the control groups, but not in the treated groups. The present results suggest a correlation between the decreasing number of hepatic egg-granulomas and the glycosylation profile of the egg-granuloma system in animals treated with free Glu.SO 4 or Glu.SO 4-LIPO.
Immunodetection of human IgG anti-Toxocara canis was developed based on ELISA and on the use of p... more Immunodetection of human IgG anti-Toxocara canis was developed based on ELISA and on the use of polysiloxane/ polyvinyl alcohol (POS/PVA) beads. A recombinant antigen was covalently immobilized, via glutaraldehyde, onto this hybrid inorganic-organic composite, which was prepared by the sol-gel technique. Using only 31.2 ng antigen per bead, a peroxidase conjugate dilution of 1:10,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates. However, the difference between positive and negative sera mean absorbances was larger for this new glass based assay. In addition to the performance of the POS/PVA bead as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.
Polyvinyl alcohol-glutaraldehyde (PVA-glut) network was synthesised in bead and disc forms and us... more Polyvinyl alcohol-glutaraldehyde (PVA-glut) network was synthesised in bead and disc forms and used for protein immobilisation. Xanthine oxidase, a-amylase and amyloglucosidase were covalently fixed on the beads yielding preparations with specific activities retention of 72.3%, 1.6% and 1.4%, respectively. Km of xanthine oxidase PVA-glut beads (24 ± 4 µM) was slightly higher than that estimated for the soluble enzyme (16
Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which w... more Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 µg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.
Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic de... more Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic derivative can be easily removed from the reaction mixture by a magnetic field. This work presents a study about the synthesis and characterization of iron phases into magnetic montmorillonite clay (mMMT) and magnetic diatomaceous earth (mDE) by 57 Fe Mössbauer spectroscopy (MS), magnetic measurements and X-ray diffraction (XRD). Also these magnetic materials were assessed as matrices for the immobilization of invertase via covalent binding. Mössbauer spectra of the magnetic composites performed at 4.2 K showed a mixture
Brazilian Journal of Medical and Biological Research, 2002
We developed an efficient method to prepare a hybrid inorganicorganic composite based on polyviny... more We developed an efficient method to prepare a hybrid inorganicorganic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 µg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 µg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.
-Galactosidase from Aspergillus oryzae is an enzyme with a wide industrial application, mostly i... more -Galactosidase from Aspergillus oryzae is an enzyme with a wide industrial application, mostly in the hydrolysis of lactose and, more recently, in the synthesis of oligosaccharides. Several advantages are associated with the application of immobilized enzymes on magnetic supports. In this work, -galactosidase was covalently immobilised onto a Polysiloxane-Polyvinyl Alcohol Magnetic Composite (mPOS-PVA), Magnetic Polysiloxane with Polyaniline (mPOS-PANI), Magnetized Dacron (DACRON) and Magnetite with Polyaniline (MAG-PANI) using glutaraldehyde as activating agent being the synthesis of GOS evaluated and compared at different temperatures (30, 40, 50 and 60 o C) and various initial lactose concentration (50, 100, 200, 300, 400 and 500 g/L). The kinetic parameters obtained by fitting the experimental data were compared in order to determine the effect of the immobilization process with different supports on the synthesis of oligosaccharides. These results clearly demonstrate that all supports may be used for -galactosidase immobilization as, besides improving the enzyme hydrolytic and GOS synthesis properties, its separation from the obtained reaction products is easy to accomplish.
The effect of different dietary concentrations of shrimp protein hydrolysate (SPH) on digestive e... more The effect of different dietary concentrations of shrimp protein hydrolysate (SPH) on digestive enzyme activity of Nile tilapia juveniles was evaluated. SPH concentrations in diets were 0, 15, 30 and 60 g kg-1 (treatments SPH0, SPH15, SPH30 and SPH60, respectively). Hemoglobin, azocasein, BApNA (Na-benzoyl-DL-arginine-p-nitroanilide), SApNA (Suc-Ala-Ala-Pro-Phe p-nitroanilide), aminoacyl of b-naphthylamide and starch were used as substrates for enzyme activity determinations. The activity of total alkaline protease was significantly higher (P \ 0.05) in fish under SPH15 and SPH60 treatments than in the control (SPH0). However, the effect was not dosedependent. Substrate-SDS-PAGE was also performed to evaluate changes in the profile
Photochemical & Photobiological Sciences, 2018
Zn(ii)meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin was applied in the photodynamic inactivation... more Zn(ii)meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin was applied in the photodynamic inactivation ofLeishmania braziliensis, leading to considerable cell damage.
International journal of biological macromolecules, Jan 25, 2018
Incorporating enzymes into calcium alginate beads is an effective method to immobilise them and t... more Incorporating enzymes into calcium alginate beads is an effective method to immobilise them and to preserve, at the same time, their catalytic activity. Sodium alginate was mixed with Aspergillus ficuum tannase in aqueous solution, and tannase-loaded calcium alginate beads were prepared using a simple droplet-based microfluidic system. Extensive experimental analysis was carried out to characterise the samples. Microscopic imaging revealed morphological differences between the surfaces of bare alginate matrix and tannase-loaded alginate beads. Thermal analysis allowed assessing the hydration contents of alginate and revealed the presence of tannase entrapped in the loaded beads, which was also confirmed by vibrational spectroscopy. X-ray diffraction allowed us to conclude that alginate of tannase-loaded beads is not crystalline, which would make them suitable as carriers for possible controlled release. Moreover, they could be used in food applications to improve tea quality or clar...
Patients with acute schistosomiasis were studied before and after oxamniquine treatment. They had... more Patients with acute schistosomiasis were studied before and after oxamniquine treatment. They had been exposed to cercariae 5 to 9 weeks before, and presented compatible clinical manifestations, eosinophilia, and high levels of total IgE. Interferon-γ (IFN-γ) and interleukin-4 were measured by ELISA in whole blood samples under soluble egg antigen or soluble adult worm preparation stimulation. After treatment, the reduction of leukocytosis and eosinophilia were not significant, but total IgE levels decreased significantly, in contrast to IFN-γ levels that were significantly increased. The oxamniquine treatment of acute schistosomiasis patients is followed by an improvement of a Th1 response in vitro. If this response has a protective aspect is unknown, and some investigations need to be realized.
This work proposes a simple, cost-effective, and efficient preparation of a composite made from m... more This work proposes a simple, cost-effective, and efficient preparation of a composite made from magnetic diatomaceous earth (mDE) coated with polyaniline (mDE@PANI). The material was used as a matrix for immobilizing industrial enzymes: invertase, β-galactosidase, and trypsin. The mDE@PANI was characterized by several methods, and the results suggested that the nanoparticles were approximately 12 nm in size, exhibited superparamagnetic behavior, and displayed a good magnetic response and that magnetite comprised the main iron oxide phase. Moreover, several studies were conducted for all immobilized derivatives, including determination of optimal pH and temperature; kinetic parameters; thermal stability and reusability. The obtainment of three novel magnetic biocatalysts with superior performance (in terms of activity and stability) compared to their free counterparts demonstrated the efficacy of the mDE@PANI nanoparticles. In addition, the enzymatic derivatives can be easily recovered from the reactor by using an external magnetic field. Finally, the present methodology allowed the achievement of good mDE@PANI matrix together with three promising magnetic biocatalysts with several potential biotechnological applications.
Anais do XX Congresso Brasileiro de Engenharia Química, 2015
Peptides with bioactive properties can be released from the precursor proteins during food proces... more Peptides with bioactive properties can be released from the precursor proteins during food processing or digestion, and act as antioxidative compounds. Although, it has been proven that hydrolysate exerts higher antioxidant activity than purified peptides. The process of enzyme immobilization proved to be more practical and advantageous for catalysis than using free enzyme. The aim of this study was to use a protease produced by Penicillium aurantiogriseum immobilized on polianilin-coated magnetic nanoparticles, for bovine casein hydrolysis and to evaluate the hydrolysate antioxidant properties. The 60-80% saline fraction of crude extract was used in immobilization. Commercial casein from bovine milk 1% (w/v) was hydrolyzed by 10 mg/mL of immobilized protease. The casein hydrolysates were used in ABTS and H 2 O 2 scavenging activity assays, where Trolox was used as standard. In the ABTS scavenging assay, the hydrolysate (1% w/v) revealed a 1341 µmol of Trolox equivalent activity and in the hydrogen peroxide scavenging assay, the hydrolysate (using 0.1% w/v) presented a 547.82 µmol of Trolox equivalent activity. In both assays the hydrolysates presented a more than 2.5 times greater activity than non-hydrolyzed casein, which validates the process capacity of developing casein derived natural antioxidant ingredients with potential for functional foods.
To investigate the effect of ions on brain acetylcholinesterase (AChE; EC 3.1.1.7) activities fro... more To investigate the effect of ions on brain acetylcholinesterase (AChE; EC 3.1.1.7) activities from economic important fish [pirarucu, Arapaima gigas; tambaqui, Colossoma macropomum; cobia, Rachycentron canadum (R. canadum) and Nile tilapia, Oreochromis niloticus (O. niloticus)] comparing with a commercial enzyme from electric eel [Electrophorus electricus (E. electricus)]. Methods: The in vitro exposure was performed at concentrations ranging from 0.001 to 10 mmol/L (except for ethylene diamine tetraacetic acid; up to 150 mmol/L). Inhibition kinetics on R. canadum and O. niloticus were also observed through four methods (Michaelis-Menten, Lineweaver-Burk, Dixon and Cornish-Bowden plots) in order to investigate the type of inhibition produced by some ions. Results: Hg 2+ , As 3+ , Cu 2+ , Zn 2+ , Cd 2+ caused inhibition in all the species under study. Ca 2+ , Mg 2+ and Mn 2+ induced slight activation in R. canadum enzyme while Pb 2+ , Ba 2+ , Fe 2+ , Li + inhibited the AChE from some of the analyzed species. The lowest IC 50 and Ki values were estimated for E. electricus AChE in presence of Hg 2+ , Pb 2+ , Zn 2+. Under our experimental conditions, the results for R. canadum and O. niloticus, As 3+ , Cu 2+ , Cd 2+ , Pb 2+ and Zn 2+ showed a noncompetitive/mixed-type inhibition, while Hg 2+ inhibited the enzyme in a mixed/competitivelike manner. Conclusions: E. electricus AChE activity was affected by ten of fifteen ions under study showing that this enzyme could undergo interference by these ions when used as pesticide biosensor in environmental analysis. This hindrance would be less relevant for the crude extracts.
Brazilian Journal of Medical and Biological Research, 2011
The antischistosomal activity of the sulfated polysaccharide α-D-glucan (Glu.SO 4) extracted from... more The antischistosomal activity of the sulfated polysaccharide α-D-glucan (Glu.SO 4) extracted from Ramalina celastri was evaluated after encapsulation into liposomes (Glu.SO 4-LIPO) in Schistosoma mansoni-infected mice. The effect of treatment with Glu.SO 4 and Glu.SO 4-LIPO (10 mg/kg) on egg elimination, worm burden and hepatic granuloma formation was assessed using female albino Swiss mice, 35-40 days of age, weighing 25 ± 2 g, infected with 150 cercariae/animal (Biomphalaria glabrata, BH strain). Four groups (N = 10) were studied, two controls (empty liposomes and NaCl) and two treated groups (Glu.SO 4-LIPO and Glu.SO 4) using a single dose. Parasitological analysis revealed that Glu.SO 4-LIPO was as efficient as Glu.SO 4 in reducing egg elimination and worm burden. Treatment with free Glu.SO 4 and Glu.SO 4-LIPO induced a statistically significant reduction in the number of granulomas (62 and 63%, respectively). Lectin histochemistry showed that wheat germ agglutinin intensely stained the egg-granuloma system in all treated groups. On the other hand, peanut agglutinin stained cells in the control groups, but not in the treated groups. The present results suggest a correlation between the decreasing number of hepatic egg-granulomas and the glycosylation profile of the egg-granuloma system in animals treated with free Glu.SO 4 or Glu.SO 4-LIPO.
Immunodetection of human IgG anti-Toxocara canis was developed based on ELISA and on the use of p... more Immunodetection of human IgG anti-Toxocara canis was developed based on ELISA and on the use of polysiloxane/ polyvinyl alcohol (POS/PVA) beads. A recombinant antigen was covalently immobilized, via glutaraldehyde, onto this hybrid inorganic-organic composite, which was prepared by the sol-gel technique. Using only 31.2 ng antigen per bead, a peroxidase conjugate dilution of 1:10,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates. However, the difference between positive and negative sera mean absorbances was larger for this new glass based assay. In addition to the performance of the POS/PVA bead as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.
Polyvinyl alcohol-glutaraldehyde (PVA-glut) network was synthesised in bead and disc forms and us... more Polyvinyl alcohol-glutaraldehyde (PVA-glut) network was synthesised in bead and disc forms and used for protein immobilisation. Xanthine oxidase, a-amylase and amyloglucosidase were covalently fixed on the beads yielding preparations with specific activities retention of 72.3%, 1.6% and 1.4%, respectively. Km of xanthine oxidase PVA-glut beads (24 ± 4 µM) was slightly higher than that estimated for the soluble enzyme (16
Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which w... more Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 µg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.
Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic de... more Magnetic particles as matrix for enzyme immobilization have been used and due to the enzymatic derivative can be easily removed from the reaction mixture by a magnetic field. This work presents a study about the synthesis and characterization of iron phases into magnetic montmorillonite clay (mMMT) and magnetic diatomaceous earth (mDE) by 57 Fe Mössbauer spectroscopy (MS), magnetic measurements and X-ray diffraction (XRD). Also these magnetic materials were assessed as matrices for the immobilization of invertase via covalent binding. Mössbauer spectra of the magnetic composites performed at 4.2 K showed a mixture
Brazilian Journal of Medical and Biological Research, 2002
We developed an efficient method to prepare a hybrid inorganicorganic composite based on polyviny... more We developed an efficient method to prepare a hybrid inorganicorganic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 µg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 µg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.
-Galactosidase from Aspergillus oryzae is an enzyme with a wide industrial application, mostly i... more -Galactosidase from Aspergillus oryzae is an enzyme with a wide industrial application, mostly in the hydrolysis of lactose and, more recently, in the synthesis of oligosaccharides. Several advantages are associated with the application of immobilized enzymes on magnetic supports. In this work, -galactosidase was covalently immobilised onto a Polysiloxane-Polyvinyl Alcohol Magnetic Composite (mPOS-PVA), Magnetic Polysiloxane with Polyaniline (mPOS-PANI), Magnetized Dacron (DACRON) and Magnetite with Polyaniline (MAG-PANI) using glutaraldehyde as activating agent being the synthesis of GOS evaluated and compared at different temperatures (30, 40, 50 and 60 o C) and various initial lactose concentration (50, 100, 200, 300, 400 and 500 g/L). The kinetic parameters obtained by fitting the experimental data were compared in order to determine the effect of the immobilization process with different supports on the synthesis of oligosaccharides. These results clearly demonstrate that all supports may be used for -galactosidase immobilization as, besides improving the enzyme hydrolytic and GOS synthesis properties, its separation from the obtained reaction products is easy to accomplish.
The effect of different dietary concentrations of shrimp protein hydrolysate (SPH) on digestive e... more The effect of different dietary concentrations of shrimp protein hydrolysate (SPH) on digestive enzyme activity of Nile tilapia juveniles was evaluated. SPH concentrations in diets were 0, 15, 30 and 60 g kg-1 (treatments SPH0, SPH15, SPH30 and SPH60, respectively). Hemoglobin, azocasein, BApNA (Na-benzoyl-DL-arginine-p-nitroanilide), SApNA (Suc-Ala-Ala-Pro-Phe p-nitroanilide), aminoacyl of b-naphthylamide and starch were used as substrates for enzyme activity determinations. The activity of total alkaline protease was significantly higher (P \ 0.05) in fish under SPH15 and SPH60 treatments than in the control (SPH0). However, the effect was not dosedependent. Substrate-SDS-PAGE was also performed to evaluate changes in the profile
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