O papel das argininas alfa-92 e alfa-141 na regulação das propriedades funcionais de hemoglobinas por íons cloreto

The oxygenation of human Hb (HbA) demands a three state model: two deoxy states To and Tx, free and complexed with anions respectively, and an oxy R state. The regulation between these states is modulated by the presence of anions, such as chloride, that binds to T state. The b inding if chloride, however, remains controversial. The aim of this work is the study of arginines 92a (a1ß2 interface) and 141a (C-terminal) as chloride binding sites. To investigate that, we have studied 92 and 141 site directed mutant species: natural mutants Hb J-Cape-Town (R92Q), desArg (R141Δ), Chesapeake (R92L), and the constructed Chesapeake desArg (R92L,141Δ). We expressed Hbs in Escherichia coli and purified. Through oxygen binding curves we measured affinity and cooperativity, in function of water effect and Bohr effect in presence and absence of chloride. Structural features were obtained through 1H NMR spectroscopy Oxygen binding properties and Bohr effect measured indicated a higher affinity and lower cooperativity in absence and presence of chloride for all mutants. Structural changes represent functional aspects of mutant Hbs, such as a significant rise in affinity or a change in cooperativity. Water activity studies conducted as a function of chloride concentration showed that the only Hb desArg follows the thre state model. The other mutant Hbs do not exhibit the Tx state, a fact confirmed by the number of water molecules bound to each Hb during the deoxy-oxy transition. This behavior suggests that the Arginine 92 site could be responsible for chloride binding to Hb, since oxygenation of 92 mutant Hbs cannot be adjusted by the three state model. However, Bohr effect showed that all mutant Hbs released~1 proton in chloride presence, different from HbA that releases ~2, suggesting a role for 141 arginine in the tertiary and quaternary Bohr effect.

Qualidade de mudas seminais de eucalipto em função dos substratos e fertilização de liberação controlada

For the production of quality seedlings, depending on the physical characteristics of each substrate, more rational nutritional managements, from the of economic-environmental point of view, should be sought. This study aimed to evaluate the development and quality of Eucalyptus grandis × E. urophylla seedlings in terms of substrates and doses of controlledrelease Osmocote® fertilizer. The experiment was conducted with a completely randomized, factorial design, using as substrates: vermiculite+carbonized rice chaff+coconut fiber (1:1:1); vermiculite+coconut fiber (1:1) and vermiculite+coconut fiber (2:1) and doses of 2, 4, 6 and 8kg·m -3 of substrate. The substrates with higher water holding capacity allow seedlings to reach their maximum development in most parameters using lower doses of controlled-release fertilizer. We recommend the application of the controlled-release fertilizer at a dose of 6.0kg·m-3 in vermiculite+carbonized rice chaff+coconut fiber (1:1:1) and vermiculite+coconut fiber (2:1) substrates, and in substrate vermiculite+coconut fiber (1:1) at a dose of 7.0kg·m-3. In each substrate there is a dose range that promotes a greater formation of suitable root systems for planting in the field, which consequently results in seedlings with greater morphological development at nursery.

Avaliação da liberação de íon fluoreto de cimentos ionoméricos antes e após a recarga e com proteção da superfície

Objective: To evaluate fluoride ion release from two anhydrous glass ionomer cements (GICs) and two resin-modified GICs (RMGICs) before and after recharge with 2% neutral sodium fluoride for 4 min and after surface protection of the Maxxion R GIC with an adhesive system, a cavity varnish and a colorless nail polish. Method: A stainless steel 2x6 mm matrix was used for fabricating 5 specimens of each material, which were immersed in 5 mL of deionized water, renewed every 24 h. Measurements with a potentiometer were performed on days 1, 2, 9 and 17, in the 1st and 2nd phases, and the specimens were buffered with a TISAB III solution. In the 2nd phase, the specimens were subjected to recharge and immersed again in 5 mL of deionized water. In the 3rd phase, the GIC surfaces were protected and readings were made at 5 min, 24 h, 48 h and 72 h. Tukey's post-hoc and Student's t tests were used for statistical analyses (p<0.05). Results: There was statistically significant difference in the comparison between the 1st and 2nd phases for all materials, except at day 2 for Vidrion R and VitroFil LC. In the 3rd phase, it was observed that for all materials, comparison of the first 5 min with the other times revealed statistically significant differences among the means of fluoride ion release. In the comparison with the other times, both the varnish and the colorless nail polish presented statistically significant difference between 24 and 48 h as well as between 24 and 72 h. Conclusion: The anhydrous GICs were more effective in fluoride ion release and recharge compared with the RMGICs. Maxxion R presented a homogeneous and statistically significant behavior in both phases. All materials for surface protection were efficient and the colorless nail polish had the best behavior.

Avaliação da liberação de potássio por resíduos do benefício de café

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Liberação de nitrogênio e potássio da palha de café em função da adubação nitrogenada

Pós-graduação em Agronomia (Agricultura) - FCA

Caracterização da interação de inositol hexafosfato e cloreto com hemoglobina humana: aspectos energéticos e estruturais

Pós-graduação em Biofísica Molecular - IBILCE

Influência da adição da espécie Acidithiobacillus ferrooxidans e de íons Cl- na dissolução da calcopirita (CuFeS'IND2')

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biossolubilização da calcopirita na presença dos íons cloreto e ácidos orgânicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Biossolubilização da calcopirita ('CU'FE'S IND. 2') na presença de íons cloreto

Pós-graduação em Biotecnologia - IQ

Estudo da concentração e recuperação de íons lantânio e neodímio por biossorção em coluna com a biomassa Sargassum sp

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Membrana transdérmica de liberação controlada utilizando quitosana, plasma e plaquetas para a regeneração de feridas

Pós-graduação em Pesquisa e Desenvolvimento (Biotecnologia Médica) - FMB

Liberação das enzimas LDH e PepX e evolução da maturação de queijo parmesão adicionado de culturas autolíticas de Lactobacilus helveticus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e caracterização físico-química de sistemas líquido cristalinos contendo palmitato de retinol: quantificação química, avaliação da atividade antioxidante, estudos de liberação e bioadesão in vitro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação, in vitro, da atividade antibacteriana, liberação de fluoreto e capacidade de recarga de cimentos de ionômero de vidro para base forradora

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Formadores de filmes híbridos orgânicos inorgânicos do tipo ureasil-poliéter para liberação controlada de fármacos

Pós-graduação em Ciências Farmacêuticas - FCFAR