Ana Lúcia Figueiredo Porto

Bio: Ana Lúcia Figueiredo Porto is an academic researcher from Universidade Federal Rural de Pernambuco. The author has contributed to research in topics: Protease & PEG ratio. The author has an hindex of 32, co-authored 273 publications receiving 3625 citations. Previous affiliations of Ana Lúcia Figueiredo Porto include Universidade Federal Rural do Rio de Janeiro & State University of Ceará.

Liquid–liquid extraction of proteases from fermented broth by PEG/citrate aqueous two-phase system

Abstract: This work deals with the use of an aqueous two-phase system (ATPS) of PEG/citrate to remove proteases from a Clostridium perfringens fermentation broth. To plan the experimental tests and evaluate the corresponding results, three successive experimental designs were employed, for which the PEG molar mass (MPEG) and concentration (CPEG), the citrate concentration (CC) and the pH were selected as independent variables, while the purification factor (PF), the partition coefficient (K), the activity yield (Y) and the selectivity (S) were selected as responses. PF of proteases in the top phase was shown to increase with increasing MPEG and decreasing CC, whereas a completely opposite trend was observed for K. On the other hand, Y was favored by simultaneous decreases in both these variables, while S decreased with increasing CC. Therefore, selecting a simultaneous increase in PF and Y as the most desirable result, the best performance of the system was obtained using MPEG = 10,000 g/mol, CPEG = 22% (w/w) and CC = 8.0% (w/w) at pH 8.5. Under these conditions, the activity yield was very high (131%) but the purification factor (4.2) and the selectivity (4.3) were lower than those ensured by more selective purification methods. According to these results, the ATPS seems to be an interesting alternative primary concentration/decontamination step for vaccine preparation from C. perfringens fermented broth.

Evidences of the static magnetic field influence on cellular systems

Abstract: Efforts to elucidate the doubtful character of the static magnetic field (SMF) influence on living cells have been made, although the topic still faces controversies because confusing reports in the scientific literature. This study intended to collect the most relevant issues separated by different topics (relating the SMF to its action on cellular systems) and analyze how the many field intensities, cell types and exposure time would affect the cell or intracellular structures. The analysis was based in the search in online databases aiming to give a general view of how the data can show conformity. It is proposed that scientists have been searching for linearity in what is actually a well characterized nonlinear system and two outputs are considered: the high sensitivity of parameters in which specific cell responses are generated and also the complexity and particularity of each cellular system. It is possible to trigger effects from a SMF, however in a stochastic way and depending on the cell system.

Quantification, Antioxidant and Antimicrobial Activity of Phenolics Isolated from Different Extracts of Capsicum frutescens (Pimenta Malagueta)

Abstract: This paper presents the quantification, antioxidant and antimicrobial activity of capsaicin, dihydrocapsaicin and the flavonoid chrysoeriol isolated from different extracts (hexane and acetonitrile extracts from whole fruit, peel and seed) of Capsicum frutescens (pimenta malagueta). The acetonitrile extract of the seeds, peel and whole fruits contained capsaicin as a major component, followed in abundance by dihydrocapsaicin and chrysoeriol. The antimicrobial activity of the isolated compounds against seven microorganisms showed chrysoeriol was the most active compound. In the antioxidant test, the acetonitrile extract from the whole fruit showed the highest activity. The antioxidant activity of pimenta malagueta may be correlated with its phenolic content, principally with the most active compound, capsaicin.

Copper Active Sites in Biology

Abstract: Based on its generally accessible I/II redox couple and bioavailability, copper plays a wide variety of roles in nature that mostly involve electron transfer (ET), O2 binding, activation and reduction, NO2− and N2O reduction and substrate activation. Copper sites that perform ET are the mononuclear blue Cu site that has a highly covalent CuII-S(Cys) bond and the binuclear CuA site that has a Cu2S(Cys)2 core with a Cu-Cu bond that keeps the site delocalized (Cu(1.5)2) in its oxidized state. In contrast to inorganic Cu complexes, these metalloprotein sites transfer electrons rapidly often over long distances, as has been previously reviewed.1–4 Blue Cu and CuA sites will only be considered here in their relation to intramolecular ET in multi-center enzymes. The focus of this review is on the Cu enzymes (Figure 1). Many are involved in O2 activation and reduction, which has mostly been thought to involve at least two electrons to overcome spin forbiddenness and the low potential of the one electron reduction to superoxide (Figure 2).5,6 Since the Cu(III) redox state has not been observed in biology, this requires either more than one Cu center or one copper and an additional redox active organic cofactor. The latter is formed in a biogenesis reaction of a residue (Tyr) that is also Cu catalyzed in the first turnover of the protein. Recently, however, there have been a number of enzymes suggested to utilize one Cu to activate O2 by 1e− reduction to form a Cu(II)-O2•− intermediate (an innersphere redox process) and it is important to understand the active site requirements to drive this reaction. The oxidases that catalyze the 4e−reduction of O2 to H2O are unique in that they effectively perform this reaction in one step indicating that the free energy barrier for the second two-electron reduction of the peroxide product of the first two-electron step is very low. In nature this requires either a trinuclear Cu cluster (in the multicopper oxidases) or a Cu/Tyr/Heme Fe cluster (in the cytochrome oxidases). The former accomplishes this with almost no overpotential maximizing its ability to oxidize substrates and its utility in biofuel cells, while the latter class of enzymes uses the excess energy to pump protons for ATP synthesis. In bacterial denitrification, a mononuclear Cu center catalyzes the 1e- reduction of nitrite to NO while a unique µ4S2−Cu4 cluster catalyzes the reduction of N2O to N2 and H2O, a 2e− process yet requiring 4Cu’s. Finally there are now several classes of enzymes that utilize an oxidized Cu(II) center to activate a covalently bound substrate to react with O2. Figure 1 Copper active sites in biology. Figure 2 Latimer Diagram for Oxygen Reduction at pH = 7.0 Adapted from References 5 and 6. This review presents in depth discussions of all these classes of Cu enzymes and the correlations within and among these classes. For each class we review our present understanding of the enzymology, kinetics, geometric structures, electronic structures and the reaction mechanisms these have elucidated. While the emphasis here is on the enzymology, model studies have significantly contributed to our understanding of O2 activation by a number of Cu enzymes and are included in appropriate subsections of this review. In general we will consider how the covalency of a Cu(II)–substrate bond can activate the substrate for its spin forbidden reaction with O2, how in binuclear Cu enzymes the exchange coupling between Cu’s overcomes the spin forbiddenness of O2 binding and controls electron transfer to O2 to direct catalysis either to perform two e− electrophilic aromatic substitution or 1e− H-atom abstraction, the type of oxygen intermediate that is required for H-atom abstraction from the strong C-H bond of methane (104 kcal/mol) and how the trinuclear Cu cluster and the Cu/Tyr/Heme Fe cluster achieve their very low barriers for the reductive cleavage of the O-O bond. Much of the insight available into these mechanisms in Cu biochemistry has come from the application of a wide range of spectroscopies and the correlation of spectroscopic results to electronic structure calculations. Thus we start with a tutorial on the different spectroscopic methods utilized to study mononuclear and multinuclear Cu enzymes and their correlations to different levels of electronic structure calculations.

Metodologia da pesquisa científica

Abstract: A Metodologia Cientifica, mais do que uma disciplina, que em principio desperta a ideia de uma linha puramente teorica, deve ser encarada como um conjunto de procedimentos sistematicos e racionais, base da formacao tanto do estudioso quanto do profissional. Ambos atuam, alem da pratica, no mundo das ideias, ou seja, suas linhas basicas caminham pelo campo teorico, porem, o acumulo do conhecimento cientifico teorico, permite a sua aplicacao pratica no desenvolvimento tecnologico, alem de sua utilizacao nas atividades profissionais. Pode-se afirmar que a pratica nasce da concepcao sobre o que deve ser realizado e qualquer tomada de decisao fundamenta-se naquilo que se afigura como o mais logico, racional, eficiente e eficaz. Desta forma, deve-se encarar a Pesquisa Cientifica e o Metodo Cientifico, que fornece os subsidios para a sua realizacao, como fundamentais para o modelo de sociedade que estamos inseridos. Os alunos devem compreender a Metodologia da Pesquisa Cientifica como um instrumento que deve auxilia a humanidade a encontrar as respostas para os problemas que surgem em nossa vida cotidiana, alem da sua importância para a elaboracao do Trabalho Cientifico, que deve ser apresentado ao final do curso de Pos-Graduacao. Para atingir este objetivo, os alunos deverao produzir um resumo cientifico.

Edible films and coatings: Structures, active functions and trends in their use

Abstract: Edible films and coatings are thin layers of edible materials applied on food products that play an important role on their conservation, distribution and marketing. Some of their functions are to protect the product from mechanical damage, physical, chemical and microbiological activities. Their use in food applications and especially highly perishable products such as horticultural ones, is based on some particular properties such as cost, availability, functional attributes, mechanical properties (flexibility, tension), optical properties (brightness and opacity), the barrier effect against gases flow, structural resistance to water and microorganisms and sensory acceptability. In this piece of work, the lastest advances on their composition (polymers to be used in the structural matrix), including nanoparticles addition, and properties have been reviewed, as well as the trends in the research about their different applications, including oil consumption reduction in deep-fat fried products, their use in combination with bioactive compounds that bring foodstuff additional functions and shelf life extension of highly perishable products.

Biosurfactants: Multifunctional Biomolecules of the 21st Century

Abstract: In the era of global industrialisation, the exploration of natural resources has served as a source of experimentation for science and advanced technologies, giving rise to the manufacturing of products with high aggregate value in the world market, such as biosurfactants. Biosurfactants are amphiphilic microbial molecules with hydrophilic and hydrophobic moieties that partition at liquid/liquid, liquid/gas or liquid/solid interfaces. Such characteristics allow these biomolecules to play a key role in emulsification, foam formation, detergency and dispersal, which are desirable qualities in different industries. Biosurfactant production is considered one of the key technologies for development in the 21st century. Besides exerting a strong positive impact on the main global problems, biosurfactant production has considerable importance to the implantation of sustainable industrial processes, such as the use of renewable resources and “green” products. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of bioremediation as well as the petroleum, food processing, health, chemical, agricultural and cosmetic industries. In this paper, we offer an extensive review regarding knowledge accumulated over the years and advances achieved in the incorporation of biomolecules in different industries.

Adhesion and aggregation ability of probiotic strain Lactobacillus acidophilus M92

Abstract: The ability of probiotic bacteria to adhere to the intestinal epithelium play an important role in colonization of the gastrointestinal tract, preventing their elimination by peristalsis and providing a competitive advantage in this ecosystem. To identify bacterial traits related to adhesion the probiotic strain L. acidophilus M92 was examined for autoaggregation ability and cell surface hydrophobicity L. acidophilus M92 exhibits a strong autoaggregation phenotype and also coaggregation with some pathogen microorganisms that may form a barrier that prevents their colonization. The examined probiotic strain manifests a good degree of hydrophobicity determined by microbial adhesion to hydrocarbons. Aggregation and hydrophobicity were abolished upon exposure of the cells to pronase, which suggests the possible role of cell surface layer (S-layer) proteins, approximated at 45 kDa, in a L. acidophilus M92. The relationship between autoaggregation and adhesion ability to intestinal tissue was investigated by observing the adhesivity of L. acidophilus M92 to porcine ileal epithelial cells. Removal of the S-layer proteins by extraction with 5 M LiCl reduced autaggregation and in vitro adhesion of this strain.