Caracteriza����o f��sico-qu��mica de pectinases extracelulares purificadas de Aspergillus giganteus

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Estudo da dopagem no ��xido de mangan��s tipo espin��lio nanoestruturado no desempenho de um sensor potenciom��trico para ��ons l��tio

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

'Beta'-D-frutofuranosidases de Fusarium graminearum: produ����o, purifica����o, imobiliza����o e determina����o das propriedades bioqu��micas de enzimas sol��veis e secas em Spray dryer

P��s-gradua����o em Biotecnologia - IQ

Estudos estruturais com miotoxinas do tipo fosfolipases A2 hom��logas do veneno de serpentes do g��nero Bothrops: avan��os no entendimento da rela����o estrutura-fun����o

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Purifica����o e caracteriza����o bioqu��mica da ��-glicosidase termoest��vel produzida por Thermoascus aurantiacus CBMAI 756

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Purifica����o e caracteriza����o bioqu��mica de poligalacturonases termoest��veis produzidas pelo fungo Thermoascus aurantiacus atrav��s de fermenta����o submersa e fermenta����o em estado s��lido

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Produ����o, isolamento e caracteriza����o de 'beta'-galactosidades de Trichoderma reesei: intera����o de ��ons met��licos na atividade enzim��tica

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Effect of divalent metal ions on the activity and stability of ��-galactosidase isolated from Kluyveromyces lactis

In this study, it was demonstrated that ��-galactosidase can be deactivated and reactivated with EDTA and divalent metal ions. The enzyme was deactivated after 20 minutes in EDTA solution. Maximal deactivation at the lowest EDTA concentration (10-3 mol.L-1) occurred in the presence of Tris-HCl buffer (pH 7.0). The enzyme recovered 50% of its initial activity after 10 minutes at Mg2+concentrations higher than 0.1 mmol.L-1. Experimental concentrations of 0.1 mmol.L-1 Mn2+ and 1.0 mmol.L-1 Co2+ were sufficient to reactivate the enzyme to around 300% of the control activity for the Mn2+ ion and nearly 100% for the Co2+ ion. The enzyme gradually lost its activity when the Co2+ concentration was 10-2 mol.L-1. Ni2+ and Zn2+ were unable to restore the catalytic activity. Km app and Vmax app were 1.95 �� 0.05 mmol.L-1 and 5.40 �� 0.86x10-2 mmol.min-1.mg-1, with o-NPG as substrate. Optimal temperature and pH were 34oC and 7.5. The half-life (t1/2) at 30��C was 17.5 min for the holoenzyme and 11.0 min for the apoenzyme. With respect to pH variation, the apoenzyme proved to be more sensitive than the holoenzyme. Keywords: ��-galactosidase. Divalent metallic ions. Enzyme activity. Stability. RESUMO Efeito de ��ons met��licos divalentes na atividade e estabilidade da ��-galactosidase isolada de Kluyveromyces lactis Este estudo demonstra como a ��-galactosidase pode ser desativada e reativada usando EDTA e ��ons met��licos divalentes. A enzima foi desativada ap��s 20 minutos na presen��a de EDTA. Desativa����o m��xima para a menor concentra����o de EDTA (10-3 mol.L-1) ocorreu na presen��a do tamp��o Tris-HCl. A enzima recuperou 50% de sua atividade inicial ap��s 10 minutos na presen��a de Mg2+ em concentra����es superiores a 0,1mmol.L-1. Concentra����es de 10-4 e 10-3mol.L-1 de Mn2+ e Co2+ foram suficientes para reativar a enzima em 300% comparado ao controle de ��ons Mn2+ e aproximadamente 100% para ��ons Co2+. A enzima perdeu gradualmente a sua atividade quando a concentra����o foi de 10-2 mol.L-1. Ni2+ e Zn2+ foram incapazes de restabelecer a atividade catal��tica. Km app e Vmax app foram 1,95 �� 0,05 mmol.L-1 e 5,40 �� 0,86 x 10-2 mmol.min-1.mg-1. A temperatura e pH ��timos foram 34��C e 7,5. A meia vida da holoenzima foi de 17,5 min a 30��C e para a apoenzima foi de 11,0 min a 30��C. Quanto �� varia����o de pH, a apoenzima provou ser mais sens��vel que a holoenzima. Palavras-chave: ��-galactosidase. ��ons met��licos divalentes. Atividade enzim��tica. Estabilidade.

Processamento e propriedades magn��ticas de manganitas multiferr��icas = Mise en forme et propri��t��s magn��tiques de manganites multiferr����ques

P��s-gradua����o em Ci��ncia e Tecnologia de Materiais - FC

Improvement of the photocatalytic activity of magnetite by Mn-incorporation

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Characterization of the co-purified invertase and beta-glucosidase of a multifunctional extract from Aspergillus terreus

The filamentous fungus Aspergillus terreus secretes both invertase and beta-glucosidase when grown under submerged fermentation containing rye flour as the carbon source. The aim of this study was to characterize the co-purified fraction, especially the invertase activity. An invertase and a beta-glucosidase were co-purified by two chromatographic steps, and the isolated enzymatic fraction was 139-fold enriched in invertase activity. SDS-PAGE analysis of the co-purified enzymes suggests that the protein fraction with invertase activity was heterodimeric, with subunits of 47 and 27 kDa. Maximal invertase activity, which was determined by response surface methodology, occurred in pH and temperature ranges of 4.0-6.0 and 55-65 A degrees C, respectively. The invertase in co-purified enzymes was stable for 1 h at pH 3.0-10.0 and maintained full activity for up to 1 h at 55 A degrees C when diluted in water. Invertase activity was stimulated by 1 mM concentrations of Mn2+ (161 %), Co2+ (68 %) and Mg2+ (61 %) and was inhibited by Al3+, Ag+, Fe2+ and Fe3+. In addition to sucrose, the co-purified enzymes hydrolyzed cellobiose, inulin and raffinose, and the apparent affinities for sucrose and cellobiose were quite similar (K-M = 22 mM). However, in the presence of Mn2+, the apparent affinity and V-max for sucrose hydrolysis increased approximately 2- and 2.9-fold, respectively, while for cellobiose, a 2.6-fold increase in V-max was observed, but the apparent affinity decreased 5.5-fold. Thus, it is possible to propose an application of this multifunctional extract containing both invertase and beta-glucosidase to degrade plant biomass, thus increasing the concentration of monosaccharides obtained from sucrose and cellobiose.

Magnetocrystalline interactions and oxidation state determination of Mn(2-x)V(1+x)O4 (x=0, 1/3 and 1) magnetorresistive spinel family

Oxidation states of transition metal cations in spinels-type oxides are sometimes extremely difficult to determine by conventional spectroscopic methods. One of the most complex cases occurs when there are different cations, each one with several possible oxidation states, as in the case of the magnetoresistant Mn(2-x)V(1+x)O4 (x=0, 1/3 and 1) spinel-type family. In this contribution we describe the determination of the oxidation state of manganese and vanadium in Mn(2-x)V(1+x)O4 (x=0, 1/3,1) spinel-type compounds by analyzing XANES and high-resolution K beta X-ray fluorescence spectra. The ionic models found are Mn22+V4+O4, Mn5/32+V4/33.5+O4 and Mn2+V23+O4. Combination of the present results with previous data provided a reliable cation distribution model. For these spinels, single magnetic electron paramagnetic resonance (EPR) lines are observed at 480 K showing the interaction among the different magnetic ions. The analysis of the EPR parameters show that g-values and relative intensities are highly influenced by the concentration and the high-spin state of Mn2+. EPR broadening linewidth is explained in terms of the bottleneck effect, which is due to the presence of the fast relaxing V3+ ion instead of the weak Mn2+ (S state) coupled to the lattice. The EPR results, at high temperature, are well explained assuming the oxidation states of the magnetic ions obtained by the other spectroscopic techniques. (c) 2013 Elsevier Inc. All rights reserved.

Effect of manganese supplementation on the membrane integrity and the mitochondrial potential of the sperm of grazing Nelore bulls

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Nanoze��litas como suportes s��lidos para imobiliza����o enzim��tica: S��ntese, caracteriza����o de complexos nanoze��litas/enzimas e sua aplica����o como catalisadores heterog��neos para produ����o de biodiesel via rota et��lica

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

S��ntese e caracteriza����o de materiais semicondutores nanoestruturados luminescentes �� base de ZnS

Conselho Nacional de Desenvolvimento Cient��fico e Tecnol��gico (CNPq)