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)

Aplica����o de Al-PILC na adsor����o de Cu²⁺, Ni²⁺ e Co²⁺ utilizando modelos f��sico-qu��micos de adsor����o

Amostra de esmectita pertencente a Serra de Maicuru (Estado do Par��, Norte do Brasil, regi��o amaz��nica) foi pilarizada com Al₁₃, A Argila pilarizada com alum��nio (Al-PILC) foi caracterizada por DRX, MEV e EDS. Para a an��lise textural foram utilizadas isotermas de adsor����o-desor����o utilizando o nitrog��nio. Este artigo �� dirigido ao estudo da adsor����o de metais pesados. A adsor����o dos ��ons de Cu²⁺, Ni²⁺e Co²⁺ foi realizadas com a matriz Al-PILC em temperatura ambiente com solu����es aquosas contendo os ��ons met��licos. Os modelos de adsor����o adotados foram os de Langmuir, Freundlich e Temkin que foram aplicados aos valores obtidos experimentalmente com regress��o linear. A equa����o de Langmuir foi o melhor modelo de lineariza����o com r = 0,999. A equa����o de Freundlich apresentou limita����es em altas concentra����es, mas foram obtidos valores (K_f e n) bastante aceit��veis utilizando este modelo. Os par��metros foram utilizados para calcular a quantidade de N_f em fun����o de Cs.

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)

S��ntese e caracteriza����o de esp��cies supramoleculares de n��quel(II) contendo piraz��is e pseudo-haletos com poss��veis aplica����es magn��ticas

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

Desenvolvimento de eletrodos de pasta de carbono modificada com 2-aminotiazol s��lica gel para a determina����o de metais em etanol combust��vel

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

Adsor����o de ��ons met��licos em meio aquoso, etan��lico e cet��nico utilizando silsesquioxanos organofuncionalizados

P��s-gradua����o em Ci��ncia dos Materiais - FEIS

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.

Reactivity of IgE to the allergen hyaluronidase from Polybia paulista (Hymenoptera, Vespidae) venom

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

Caracteriza����o funcional da prote��na XAC1201 envolvida na patogenicidade de Xanthomonas citri subsp. citri

P��s-gradua����o em Agronomia (Gen��tica e Melhoramento de Plantas) - FCAV

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)

Estudos experimentais e te��rico-computacionais de novos complexos nanoze��litas-enzimas empregados na produ����o de biocombust��veis

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

Metal binding selectivity of oxa-aza macrocyclic ligand: a DFT study of first- and second-row transition metal for four coordination systems

A detailed theoretical study of the 1,7,1l,17-tetraoxa-2,6,12,16-tetraaza-cycloeicosane ligand ([20]AneN(4)O(4)) coordinated to Fe2+, Co2+, Ni2+, Ru2+, Rh2+, and Pd2+ transition metal ions was carried out with the B3LYP method. Two different cases were performed: when nitrogen is the donor atom (1a (q) ) and also with the oxygen as the donor atom (1b (q) ). For all the cases performed in this study 1a (q) structures were always more stable than the 1b (q) ones. Considering each row is possible to see that the energy increases with the increase of the atomic number. The M2+ cation binding energies for the 1a (q) complexes increase with the following order: Fe2+ < Ru2+ < Co2+ < Ni2+ < Rh2+ < Pd2+.

Synthetic Phytochelatin Surface Display in Cupriavidus metallidurans CH34 for Enhanced Metals Bioremediation

This work describes the effects of the cell surface display of a synthetic phytochelatin in the highly metal tolerant bacterium Cupriavidus metallidurans CH34. The EC20sp synthetic phytochelatin gene was fused between the coding sequences of the signal peptide (SS) and of the autotransporter beta-domain of the Neisseria gonorrhoeae IgA protease precursor (IgA beta), which successfully targeted the hybrid protein toward the C. metallidurans outer membrane. The expression of the SS-EC20sp-IgA beta gene fusion was driven by a modified version of the Bacillus subtilis mrgA promoter showing high level basal gene expression that is further enhanced by metal presence in C. metallidurans. The recombinant strain showed increased ability to immobilize Pb2+, Zn2+, Cu2+, Cd2+, Mn2+, and Ni2+ ions from the external medium when compared to the control strain. To ensure plasmid stability and biological containment, the MOB region of the plasmid was replaced by the E. coli hok/sok coding sequence.

In Situ Quantification of Cu(II) during an Electrodeposition Reaction Using Time-Domain NMR Relaxometry

The use of a low-cost benchtop time-domain NMR (TD-NMR) spectrometer to monitor copper electrodeposition in situ is presented. The measurements are based on the strong linear correlation between the concentration of paramagnetic ions and the transverse relaxation rates (R-2) of the solvent protons Two electrochemical NMR (EC-NMR) cells were constructed and applied to monitor the Cu2+ concentration during the electrodeposition reaction. The results show that TD-NMR relaxometry using the Carr-Purcell-Meiboom-Gill pulse sequence can be a very fast, simple, and efficient technique to monitor, in real time, the variation in the Cu2+ concentration during an electrodeposition reaction. This methodology can also be applied to monitor the electrodeposition of other paramagnetic ions, such as Ni2+ and Cr3+, which are commonly used in electroplating.

Immobilization of a recombinant endo-1,5-arabinanase secreted by Aspergillus nidulans strain A773

An endo-1,5-arabinanase (abnA) encoding gene from Aspergillus niveus was identified, cloned and successfully expressed in Aspergillus nidulans strain A773. Based on amino acid sequence comparison, the 34-kDa enzyme could be assigned to CAZy GH family 43. Characterization of purified recombinant endo-1,5-arabinanase (AbnA) revealed that it is active at a wide pH range (pH 4.0-7.0) and an optimum temperature at 70 degrees C. The immobilization of the AbnA was performed via covalent binding onto agarose-modified supports: glyoxyl iminodiacetic acid-Ni2+, glyoxyl amine, glyoxyl (4% and 10%) and cyanogen bromide activated sepharose. The yield of immobilization was similar on glyoxyl amine and glyoxyl (96%), and higher than glyoxyl iminodiacetic acid-Ni2+ (43%) support. The thermal inactivation of these immobilized preparations showed that the stability of the AbnA immobilized on glyoxyl 4 and 10% was improved by 4.0 and 10.3-fold factor at 70 degrees C. The half-life of glyoxyl 4% derivative at 60 degrees C was >48 h (pH 5), 9 h (pH 7) and 88 min (pH 9). The major hydrolysis product of debranched arabinan or arabinopentaose by glyoxyl agarose-immobilized AbnA was arabinobiose. (C) 2012 Elsevier B.V. All rights reserved.