Electric field effects on β-lactoglobulin thermal unfolding as a function of pH Impact on protein functionality

The presence of moderate electric fields (MEF) during ohmic heating (OH) treatment of whey protein systems have demonstrated potential to change physicochemical and functional properties, like aggregation rate and extension or viscoelastic behaviour. However, the specific action of MEF upon the molecular structure of proteins, particularly during thermal processing has yet to be clarified. The effects of MEF in pure fractions of -lactoglobulin (β-lg) under non-aggregating conditions (low concentration and ionic strength), were investigated in this work. Protein samples were identically heat-treated through conventional and OH methods and at different pH values. β-lg's structural features were characterized by evaluation of secondary structure distribution and local conformational changes using techniques such as circular dichroism, intrinsic and extrinsic fluorescence and free thiol groups reactivity. It was confirmed that MEF affects β-lg upon thermal unfolding, resulting in distinctive structural features, surface hydrophobicity and SH reactivity. The mechanism of action is probably related with the molecular motion induced by the oscillating electric field and is more pronounced at neutral pH, where β-lg is more susceptible to thermal structural changes. These results contribute to a better understanding of OH processing and its effects in food matrices reinforce the possibility of using MEF as a toll to change protein functionality. Industrial relevance Ohmic heating is an emerging technology and is being established as reference method for processing protein-rich food such as dairy and egg products. Non-thermal effects of the applied electric fields during ohmic heating have been addressed but few works deal with their real impact in structural and molecular properties of food proteins with high biological value. In this work demonstrated that the presence of an electric field during ohmic heating processing influences structural aspects of beta-lactoglobulin. This knowledge plays an important role on process design (i.e. pasteurization binomials and fouling control) and product quality because these proteins play an essential role in food's nutritional and organoleptic properties, as well as on functionality, allergenicity and stability aspects.FCT -Fuel Cell Technologies Program(NORTE-01-0145-FEDER-000004)info:eu-repo/semantics/publishedVersio

Avances en modelos de análisis de estructuras de barras de hormigón frente a combinaciones de esfuerzos normales y tangentes

A pesar del gran desarrollo de los modelos de barras para el análisis estructural, estos modelos presentan, en general, carencias importantes cuando las estructuras son sensibles a esfuerzos tangenciales (cortante, torsión) o cuando existen estados tridimensionales complejos. Estas solicitaciones, muy comunes en las estructuras de ingeniería civil, son mucho más complejas de analizar en el caso de materiales que presentan comportamiento anisótropo dependiente de la carga, como es el caso del hormigón armado. Se presentan los modelos desarrollados en los últimos años para tener en cuenta este comportamiento satisfactoriamente, facilitando así el análisis de estructuras bajo fuertes combinaciones de esfuerzos normales y tangentes, como pueden darse en estructuras bajo acciones sísmicas

CONTAMINAÇÃO DO SOLO E DA ÁGUA PELO USO DE AGROTÓXICOS

The increase of the world population and the need to elevate food production improved the agriculture used techniques. One of the most important change that happened in the form and in the mean of agricultural production was pesticides. These products are used to control of insects, diseases and weeds that damage the cultures development. However, the intense application of these in the agricultural areas has been causing the contamination and pollution of the soil, water and air. These resources are indispensable for the human and animal survival in the Planet. In the last decades an increase of the world concern was verified regarding the impact that certain practices cause to the environment among abusive use of pesticides. When applied in the cultures, the pesticides usually reach the soil and, depending on the edaphic and product characteristics and of the environmental conditions, these products could do the ecosystem contamination. In this review are approached to the contamination of the soil and superficial and underground waters for the current pesticides use in the agricultural systems, as well as practices and handling forms that help the environment preservation.O aumento da população mundial e a necessidade de elevar a produção de alimentos revolucionaram as técnicas utilizadas na agricultura. Uma das mais importantes mudanças que ocorreram na forma e nos meios de produção agrícola foi a utilização de agrotóxicos, produtos estes utilizados para o controle de insetos, doenças e plantas invasoras que prejudicam o desenvolvimento das culturas. No entanto, a intensa aplicação destes insumos nas áreas agrícolas tem ocasionado a contaminação e poluição do solo, da água e do ar, recursos estes indispensáveis para a sobrevivência humana e animal no Planeta. Nas últimas décadas, verificou-se um aumento da preocupação mundial a respeito do impacto que determinadas práticas causam ao meio ambiente, dentre elas o uso abusivo de agrotóxicos. Estes quando aplicados nas culturas, normalmente atingem o solo e, dependendo das características edáficas, do produto utilizado e das condições ambientais, podem provocar a contaminação do ecossistema. Nesta revisão são abordados aspectos referentes à contaminação do solo e das águas superficiais e subterrâneas pelo decorrente uso de agrotóxicos nos sistemas agrícolas, bem como práticas e formas de manejo que visam a preservação do meio ambiente

NATIVE COLLEMBOLA REPRODUCTION IN LABORATORY CONDITIONS

Estudos utilizando a fauna ed\ue1fica como bioindicador da qualidade do solo t\ueam sido de grande import\ue2ncia para entender as varia\ue7\uf5es f\uedsicas, qu\uedmicas e biol\uf3gicas de ecossistemas. Dentre os organismos estudados, os col\ueambolos constituem um dos principais grupos. Este trabalho teve como objetivo avaliar a multiplica\ue7\ue3o de col\ueambolos nativos em condi\ue7\uf5es de laborat\uf3rio. Como substrato, utilizaram-se amostras de solo coletadas em \ue1rea de citrus e bosque de pinus, com os tratamentos: a) amostra de solo de \ue1rea de c\uedtrus com palha de ervilhaca mo\uedda, palha de milho mo\uedda, palha de nabo mo\uedda, cama de avi\ue1rio mo\uedda e amostra de solo e, b) em solo de bosque de pinus com: palha de ervilhaca mo\uedda, palha de milho mo\uedda, palha de nabo mo\uedda, cama de avi\ue1rio mo\uedda e amostra de solo. Os tratamentos foram mantidos em potes pl\ue1sticos, a 26\ub0C, no escuro, sendo realizadas cinco avalia\ue7\uf5es durante o per\uedodo de 180 dias. O solo de pomar de c\uedtrus com adi\ue7\ue3o de palha de nabo mo\ueddo favoreceu a reprodu\ue7\ue3o destes organismos em condi\ue7\uf5es de laborat\uf3rio.The use of soil fauna as soil quality indicator has been of great importance to understand the biological, chemical and physical variations of ecosystems. The collembola takes part in a group of organisms that has an active participation in organic material transformations of soil. The aim of this work was to evaluate the collembola reproduction in laboratory condition. The used substrate was sample of soil collected from citrus and pinus area with the following treatments: a) citrus soil with: common vetch ground straw, corn ground straw, turnip ground straw, broiller litter and in soil and, b) pinus soil with: common vetch ground straw, corn ground straw, turnip ground straw, broiller litter and in soil. The treatments were maintained in plastic pots at 26\ub0C in the darkness, during 180 days, with five repetitions. The soil material from citrus area with turnip ground straw favored the collembola reproduction in laboratory conditions

Determination of thermally-induced conformational slides in β-lactoglobulin prior to irreversible thermal denaturation

IFT 2017 Annual Meeting and Food Expo[Excerpt] Introduction: β-lactoglobulin (β-Lg) is the major globular protein in milk and the dominant functional agent in whey and its derivatives ingredients. It is generally recognized that β-Lg undergoes conformational changes above temperatures of 60 °C and unfolds irreversibly after 70 °C. The conformational changes that happen during this process have critical implications in β-Lg functional properties, thus affecting both technological quality of milk (i.e. cheese production) and whey ingredients, which use are currently widespread in food formulations. In this study thermal effects in β-Lg have been investigated through an innovative approach, combining on-line spectroscopy techniques, aiming at achieving a more detailed characterization of these events below and above the melting temperature. [...]This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors Rui M. Rodrigues, Ricardo N. Pereira, also thank to FCT their financial grants with SFRH/BD/110723/2015, SFRH/BPD/81887/2011 respectively.info:eu-repo/semantics/publishedVersio

Complete enzymic synthesis of the mucin-type sialyl Lewis x epitope, involved in the interaction between PSGL-1 and P-selectin

Sialyl Lewis x (sLex) is an established selectin ligand occurring on N- and O-linked glycans. Using a completely enzymic approach starting from p-nitrophenyl N-acetyl-α-D-galactosaminide (GalNAc(α1-pNp as core substrate, the sLex-oligosaccharide Neu5Ac(α2-3)Gal(β1-4)[Fuc(α1-3)]GlcNAc(β1-6)[Gal(β1-3)]GalNAc(α1-pNp, representing the O-linked form, was synthesized in an overall yield of 32%. In a first step, Gal(β1-3)GalNAc(α1-pNp was prepared in a yield of 52% using UDP-Gal and an enriched preparation of β3-galactosyltransferase (EC 2.4.1.122) from rat liver. UDP-GlcNAc and a recombinant affinity-purified preparation of core 2 β6-N-acetylglucosaminyltransferase (EC 2.4.1.102) fused to Protein A were used to branch the core 1 structure, affording GlcNAc(β1-6)[Gal(β1-3)]GalNAc(α1-pNp in a yield of >85%. The core 2 structure was galactosylated using UDP-Gal and purified human milk β4-galactosyltransferase 1 (EC 2.4.1.38) (yield of >85%), then sialylated using CMP-Neu5Ac and purified recombinant α3-sialyltransferase 3 (EC 2.4.99.X) (yield of 87%), and finally fucosylated using GDP-Fuc and recombinant human α3-fucosyltransferase 6 (EC 2.4.1.152) produced in Pichia pastoris (yield of 100%). Overall 1.5 µmol of product was prepared. MALDI TOF mass spectra, and 1D and 2D TOCSY and ROESY 1H NMR analysis confirmed the obtained structur

Effects of moderate electric fields in beta-lactoglobulinthermal denaturation: structural changes and binding properties

This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Rui M. Rodrigues gratefully acknowledge FCT for their financial grant with reference SFRH/BD/110723/2015.info:eu-repo/semantics/publishedVersio