Uncovering the Association Mechanism between Two Intrinsically Flexible Proteins.

The understanding of protein-protein interaction mechanisms is key to the atomistic description of cell signaling pathways and for the development of new drugs. In this context, the mechanism of intrinsically disordered proteins folding upon binding has attracted attention. The VirB9 C-terminal domain (VirB9Ct) and the VirB7 N-terminal motif (VirB7Nt) associate with VirB10 to form the outer membrane core complex of the Type IV Secretion System injectisome. Despite forming a stable and rigid complex, VirB7Nt behaves as a random coil, while VirB9Ct is intrinsically dynamic in the free state. Here we combined NMR, stopped-flow fluorescence, and computer simulations using structure-based models to characterize the VirB9Ct-VirB7Nt coupled folding and binding mechanism. Qualitative data analysis suggested that VirB9Ct preferentially binds to VirB7Nt by way of a conformational selection mechanism at lower temperatures. However, at higher temperatures, energy barriers between different VirB9Ct conformations are more easily surpassed. Under these conditions the formation of non-native initial encounter complexes may provide alternative pathways toward the native complex conformation. These observations highlight the intimate relationship between folding and binding, calling attention to the fact that the two molecular partners must search for the most favored intramolecular and intermolecular interactions on a rugged and funnelled conformational energy landscape, along which multiple intermediates may lead to the final native state.

PEGylation versus glycosylation: effect on the thermodynamics and thermostability of crisantaspase.

Thermostability is an important and desired feature of therapeutic proteins and is critical for the success or failure of protein drugs development. It can be increased by PEGylation-binding of poly(ethylene glycol) moieties-or glycosylation-post-translational modification to add glycans. Here, the thermostability and thermodynamic parameters of native, PEGylated, and glycosylated versions of the antileukemic enzyme crisantaspase were investigated. First-order kinetics was found to describe the irreversible deactivation process. Activation energy of the enzyme-catalyzed reaction (E*) was estimated for native, PEGylated, and glycosylated enzyme (10.2, 14.8, and 18.8 kJ mol-1 respectively). Half-life decreased progressively with increasing temperature, and longer half-life was observed for PEG-crisantaspase (87.74 min) at 50 °C compared to the native form (9.79 min). The activation energy of denaturation of PEG-crisantaspase (307.1 kJ mol-1) was higher than for crisantaspase (218.1 kJ mol-1) and Glyco-crisantaspase (120.0 kJ mol-1), which means that more energy is required to overcome the energy barrier of the unfolding process. According to our results, PEG-crisantaspase is more thermostable than its native form, while Glyco-crisantaspase is more thermosensitive.

Structural analysis of TrkA mutations in patients with congenital insensitivity to pain reveals PLCγ as an analgesic drug target.

Chronic pain is a major health issue, and the search for new analgesics has become increasingly important because of the addictive properties and unwanted side effects of opioids. To explore potentially new drug targets, we investigated mutations in the NTRK1 gene found in individuals with congenital insensitivity to pain with anhidrosis (CIPA). NTRK1 encodes tropomyosin receptor kinase A (TrkA), the receptor for nerve growth factor (NGF) and that contributes to nociception. Molecular modeling and biochemical analysis identified mutations that decreased the interaction between TrkA and one of its substrates and signaling effectors, phospholipase Cγ (PLCγ). We developed a cell-permeable phosphopeptide derived from TrkA (TAT-pQYP) that bound the Src homology domain 2 (SH2) of PLCγ. In HEK-293T cells, TAT-pQYP inhibited the binding of heterologously expressed TrkA to PLCγ and decreased NGF-induced, TrkA-mediated PLCγ activation and signaling. In mice, intraplantar administration of TAT-pQYP decreased mechanical sensitivity in an inflammatory pain model, suggesting that targeting this interaction may be analgesic. The findings demonstrate a strategy to identify new targets for pain relief by analyzing the signaling pathways that are perturbed in CIPA.

COVID-19: a influência de fatores psicossociais na crença acerca da pertinência do isolamento social no Brasil / COVID-19: The influence of psychosocial factors in the belief of relevance of social isolation in Brazil / COVID-19: la influencia de los factores psicosociales en la creencia sobre la relevancia del aislamiento social en Brasil

A pandemia de COVID-19 impele a compreensão de diferentes aspectos que condicionam a formação da percepção social acerca deste fenômeno. Este estudo teve como objetivo identificar variáveis psicossociais que predizem a adesão à crença de que isolamento social previne o contágio de COVID-19. Para isto se realizou um estudo correlacional, no qual responderam a um questionário online 498 participantes com idade média de 34,9 anos. Um questionário sociodemográfico, escalas de atitudes e crenças em saúde compuseram os instrumentos de pesquisa. Análises descritivas, correlações e análise de regressão linear múltipla foram utilizadas. Os resultados demonstraram que atitudes políticas contribuem na formação da crença acerca do isolamento social no contexto da COVID-19. As interrelações demonstraram que identidades políticas desempenham papel importante na adesão aos discursos de instituições sanitárias ou políticas. Evidencia-se que dimensões psicossociais devem ser levadas em consideração no enfrentamento ao contágio da COVID-19.

The pandemic of the COVID-19 can lead to understanding several aspects of the social formation perception about this phenomenon. This study aimed to identify psychosocial variables that predict the adoption of the belief that social isolation prevents the infection of COVID-19. A correlational study was used with 498 people who answered an online questionnaire. The average age was 34.9 years. The research instrument was composed of sociodemographic questionnaire, scales of attitudes and health beliefs mode scale. Descriptive analysis, correlations and multiple linear regression analysis were used. The results revealed that political attitudes contribute to the formation of the belief about social isolation in the context of COVID-19. Interrelations have shown that political identities have an important role in adhering to the policies of health or political institutions. It has been shown that psychosocial dimensions must be taken into account when facing the contagion from COVID-19.

La pandemia del COVID-19 requiere comprender diferentes aspectos que condicionan la formación de la percepción social sobre este fenómeno. El objetivo de este estudio fue identificar las variables psicosociales que predicen la adopción de la creencia de que el aislamiento social previene el contagio de COVID-19. Se realizó un estudio correlacional, en el que 498 participantes con una edad promedio de 34,9 años respondieron un cuestionario online. Los instrumentos de investigación fueron: un cuestionario sociodemográfico, escalas de actitudes y creencias en salud. Se utilizaron análisis descriptivos, correlaciones y análisis de regresión lineal múltiple. Los resultados demostraron que las actitudes políticas contribuyen a la formación de la creencia sobre el aislamiento social en el contexto de COVID-19. Las interrelaciones han demostrado que las identidades políticas desempeñan un papel importante en la adhesión a los discursos de las instituciones sanitarias o las instituciones políticas. Se evidencia que hay que tener en cuenta las dimensiones psicosociales cuando se trata del contagio del COVID-19.

Lysine-PEGylated Cytochrome C with Enhanced Shelf-Life Stability.

Cytochrome c (Cyt-c), a small mitochondrial electron transport heme protein, has been employed in bioelectrochemical and therapeutic applications. However, its potential as both a biosensor and anticancer drug is significantly impaired due to poor long-term and thermal stability. To overcome these drawbacks, we developed a site-specific PEGylation protocol for Cyt-c. The PEG derivative used was a 5 kDa mPEG-NHS, and a site-directed PEGylation at the lysine amino-acids was performed. The effects of the pH of the reaction media, molar ratio (Cyt-c:mPEG-NHS) and reaction time were evaluated. The best conditions were defined as pH 7, 1:25 Cyt-c:mPEG-NHS and 15 min reaction time, resulting in PEGylation yield of 45% for Cyt-c-PEG-4 and 34% for Cyt-c-PEG-8 (PEGylated cytochrome c with 4 and 8 PEG molecules, respectively). Circular dichroism spectra demonstrated that PEGylation did not cause significant changes to the secondary and tertiary structures of the Cyt-c. The long-term stability of native and PEGylated Cyt-c forms was also investigated in terms of peroxidative activity. The results demonstrated that both Cyt-c-PEG-4 and Cyt-c-PEG-8 were more stable, presenting higher half-life than unPEGylated protein. In particular, Cyt-c-PEG-8 presented great potential for biomedical applications, since it retained 30-40% more residual activity than Cyt-c over 60-days of storage, at both studied temperatures of 4 °C and 25 °C.

Naphthalimide-Containing BP100 Leads to Higher Model Membranes Interactions and Antimicrobial Activity.

In a large variety of organisms, antimicrobial peptides (AMPs) are primary defenses against pathogens. BP100 (KKLFKKILKYL-NH2), a short, synthetic, cationic AMP, is active against bacteria and displays low toxicity towards eukaryotic cells. BP100 acquires a α-helical conformation upon interaction with membranes and increases membrane permeability. Despite the volume of information available, the action mechanism of BP100, the selectivity of its biological effects, and possible applications are far from consensual. Our group synthesized a fluorescent BP100 analogue containing naphthalimide linked to its N-terminal end, NAPHT-BP100 (Naphthalimide-AAKKLFKKILKYL-NH2). The fluorescence properties of naphthalimides, especially their spectral sensitivity to microenvironment changes, are well established, and their biological activities against transformed cells and bacteria are known. Naphthalimide derived compounds are known to interact with DNA disturbing related processes as replication and transcription, and used as anticancer agents due to this property. A wide variety of techniques were used to demonstrate that NAPHT-BP100 bound to and permeabilized zwitterionic POPC and negatively charged POPC:POPG liposomes and, upon interaction, acquired a α-helical structure. Membrane surface high peptide/lipid ratios triggered complete permeabilization of the liposomes in a detergent-like manner. Membrane disruption was driven by charge neutralization, lipid aggregation, and bilayer destabilization. NAPHT-BP100 also interacted with double-stranded DNA, indicating that this peptide could also affect other cellular processes besides causing membrane destabilization. NAPHT-BP100 showed increased antibacterial and hemolytic activities, compared to BP100, and may constitute an efficient antimicrobial agent for dermatological use. By conjugating BP100 and naphthalimide DNA binding properties, NAPHT-BP100 bound to a large extent to the bacterial membrane and could more efficiently destabilize it. We also speculate that peptide could enter the bacteria cell and interact with its DNA in the cytoplasm.

Pegylated catalase as a potential alternative to treat vitiligo and UV induced skin damage.

The metabolic function of catalase (CAT) is to prevent oxidative damage to tissues through the hydrolysis of hydrogen peroxide, which is a strong oxidizing agent. It has been suggested as an alternative to treat skin diseases related to oxidative stress, such as vitiligo. Owing to the instability associated to the protein nature, topical use of CAT is challenging and, in this sense, PEGylation can be an interesting alternative. Here, we conjugated CAT to methoxy-poly(ethylene oxide) (mPEG) of 10, 20 and 40 kDa, by means of a nucleophilic attack of ε-amino groups to an electron-deficient carbonyl group of the reactive PEG, resulting in site specifically PEGylated bioconjugates. PEGylation yields ranged from 31% ± 2% for CAT-PEG40 to 59% ± 4% for CAT-PEG20 and were strongly affected by the reaction pH owing to the protonation/deprotonation state of primary amines of lysine and N-terminal residues. PEGylated conjugates were purified by size-exclusion chromatography (purity > 95%) and characterized by circular dichroism. Irrespectively of MW, PEG did not affected CAT secondary and tertiary structure, but a decrease in specific activity was observed, more pronounced when PEGs of higher MWs were used. However, this loss of activity is compensated by the increased long-term stability, with a gain of >5 times in t1/2. In vitro antioxidant activity of CAT-PEG20 showed complete elimination of lipid peroxidation at the skin upper layer (stratum corneum) suitable for a topical use to treat vitiligo, as well as other skin conditions related to oxidative stress.

Characterization of phospholipid vesicles containing lauric acid: physicochemical basis for process and product development.

Lauric acid (LAH) strongly inhibits the growth of acne-causing bacteria. LAH is essentially water-insoluble and the solubility of laurate (LA) salts are medium and temperature dependent. Hence, LAH/LA preparations are difficult to formulate. Here we fully characterized phospholipid vesicles containing up to 50 mol% LAH. Vesicles of dipalmitoylphosphatidylcholine (DPPC) containing LAH, at pHs 7.4 and 5.0, were characterized measuring size, charge, bilayer phase transition temperature (Tm) and permeability of water-soluble probes. Small angle X-ray scattering and cryotransmission electron microscopy showed multilamellar vesicles at low LAH %. Increasing LAH % had a negligible effect on particle size. An internal aqueous compartment in all vesicle's preparations, even at equimolar DPPC: LAH fractions, was demonstrated using water-soluble probes. At pH 5.0, the interaction between DPPC and LAH increased the Tm and phase transition cooperativity showing a single lipid phase formed by hydrogen-bonded DPPC: LAH complexes. At pH 7.4, vesicles containing 50 mol% LAH exhibited distinct phases, ascribed to complex formation between LAH and LA or LAH and DPPC. LAH incorporated in the vesicles minimally permeated a skin preparation at both pHs, indicating that the primary sites of LAH solubilization were the skin layers. These results provide the foundations for developing processes and products containing DPPC: LAH.

Transformações do capitalismo e formação do indivíduo: contribuições da Escola de Frankfurt na análise das eleições presidenciais nos EUA e Brasil / Capitalism's transformations and individual's formation: contributions of the Frankfurt School in the analysis of the presidential elections in the USA and Brazil

O artigo teve como referencial teórico as contribuições dos autores da primeira geração da Escola de Frankfurt. Ele visa apresentar, em termos gerais, as alterações que ocorreram no capitalismo nos séculos XIX e XX e os impactos delas na formação do indivíduo - ainda percebidos na contemporaneidade. Para tanto, são apresentadas características do capitalismo liberal e monopolista, assim como da ideologia produzida por tais configurações desse sistema produtivo. A partir disso, é destacado como tais elementos incidem na formação do indivíduo e como há alterações em sua função social: da oposição para a adesão. Para tanto, são analisados alguns fenômenos psicossociais ocorridos nas últimas eleições presidenciais nos EUA e no Brasil. Se algumas proposições da primeira geração da Escola de Frankfurt se tornam anacrônicas, quanto aos meios, as contribuições a respeito da manipulação da massa se tornam extremamente atuais. A redução de indivíduos a algoritmos, passíveis de manipulação, demonstra a falência do modelo de individualidade burguês. Longe de ser uma referência nostálgica ao modelo liberal de indivíduo, o artigo visa demonstrar as contradições da formação do indivíduo na contemporaneidade.(AU)

This paper has as theoretical reference the contributions of the authors of the first generation of the Frankfurt School. It aims to present the changes occurred in capitalism in the XIX and XX centuries and their impact in individual's formation - still noticed nowadays. Therefore, characteristics of the liberal and monopoly capitalism are presented, as well as the ideology produced by such configurations of the production system. From this, it is highlighted as these elements affect the formation of the individual and how there are changes in its social function: opposition to adhesion. In order to do so, it has been analyzed some psychosocial phenomena that occurred in the last presidential elections in the USA and Brazil. If some propositions of the first generation of the Frankfurt School become anachronistic, as to the means, the contributions regarding mass manipulation become extremely actual. The reduction of individuals to algorithms demonstrates the bankruptcy of the model of bourgeois individuality. Far from being a nostalgic reference to the liberal model of individual, the article aims to demonstrate its contradictions in the contemporary world.(AU)

Violacein Targets the Cytoplasmic Membrane of Bacteria.

Violacein is a tryptophan-derived purple pigment produced by environmental bacteria, which displays multiple biological activities, including strong inhibition of Gram-positive pathogens. Here, we applied a combination of experimental approaches to identify the mechanism by which violacein kills Gram-positive bacteria. Fluorescence microscopy showed that violacein quickly and dramatically permeabilizes B. subtilis and S. aureus cells. Cell permeabilization was accompanied by the appearance of visible discontinuities or rips in the cytoplasmic membrane, but it did not affect the cell wall. Using in vitro experiments, we showed that violacein binds directly to liposomes made with commercial and bacterial phospholipids and perturbs their structure and permeability. Furthermore, molecular dynamics simulations were employed to reveal how violacein inserts itself into lipid bilayers. Thus, our combined results demonstrate that the cytoplasmic membrane is the primary target of violacein in bacteria. The implications of this finding for the development of violacein as a therapeutic agent are discussed.

Self-association and folding in membrane determine the mode of action of peptides from the lytic segment of sticholysins.

Sticholysin I and II (Sts: St I and St II) are proteins of biomedical interest that form pores upon the insertion of their N-terminus in the plasma membrane. Peptides spanning the N-terminal residues of StI (StI1-31) or StII (StII1-30) can mimic the permeabilizing ability of these toxins, emerging as candidates to rationalize their potential biomedical applications. These peptides have different activities that correlate with their hydrophobicity. However, it is not clear how this property contributes to peptide folding in solution or upon binding to membranes. Here we compared the conformational properties of these peptides and shorter versions lacking the hydrophobic segment 1-11 of StI (StI12-31) or 1-10 of StII (StII11-30). Folding of peptides was assessed in solution and in membrane mimetic systems and related with their ability to bind to membranes and to permeabilize lipid vesicles. Our results suggest that the differences in activity among peptides could be ascribed to their different folding propensity and different membrane binding properties. In solution, StII1-30 tends to acquire α-helical conformation coexisting with self-associated structures, while StI1-31 remains structureless. Both peptides fold as α-helix in membrane; but StII1-30 also self-associates in the lipid environment, a process that is favored by its higher affinity for membrane. We stress the contribution of the non-polar/polar balance of the 1-10 amino acid sequence of the peptides as a determining factor for different self-association capabilities. Such difference in hydrophobicity seems to determine the molecular path of peptides folding upon binding to membranes, with an impact in their permeabilizing activity. This study contributes to a better understanding of the molecular mechanisms underlying the permeabilizing activity of Sts N-terminal derived peptides, with connotation for the exploitation of these small molecules as alternative of the full-length toxins in clinical settings.

Dissecting the mechanism of action of actinoporins. Role of the N-terminal amphipathic α-helix in membrane binding and pore activity of sticholysins I and II.

Actinoporins sticholysin I and sticholysin II (St I, St II) are proposed to lyse model and biomembranes via toroidal pore formation by their N-terminal domain. Based on the hypothesis that peptide fragments can reproduce the structure and function of this domain, the behavior of peptides containing St I residues 12-31 (StI12-31), St II residues 11-30 (StII11-30), and its TOAC-labeled analogue (N-TOAC-StII11-30) was examined. Molecular modeling showed a good match with experimental structures, indicating amphipathic α-helices in the same regions as in the toxins. CD spectra revealed that the peptides were essentially unstructured in aqueous solution, acquiring α-helical conformation upon interaction with micelles and large unilamellar vesicles (LUV) of variable lipid composition. Fluorescence quenching studies with NBD-containing lipids indicated that N-TOAC-StII11-30's nitroxide moiety is located in the membranes polar head group region. Pyrene-labeled phospholipid inter-leaflet redistribution suggested that the peptides form toroidal pores, according to the mechanism of action proposed for the toxins. Binding occurred only to negatively charged LUV, indicating the importance of electrostatic interactions; in contrast the peptides bound to both negatively charged and zwitterionic micelles, pointing to a lesser influence of these interactions. In addition, differences between bilayers and micelles in head group packing and in curvature led to differences in peptide-membrane interaction. We propose that the peptides topography in micelles resembles that of the toxins in the toroidal pore. The peptides mimicked the toxins permeabilizing activity, St II peptides being more effective than StI12-31. To our knowledge, this is the first demonstration that differences in the toxins N-terminal amphipathic α-helix play a role in the difference between St I and St II activities.

Synthesis, biophysical and functional studies of two BP100 analogues modified by a hydrophobic chain and a cyclic peptide.

Antimicrobial peptides (AMPs) work as a primary defense against pathogenic microorganisms. BP100, (KKLFKKILKYL-NH2), a rationally designed short, highly cationic AMP, acts against many bacteria, displaying low toxicity to eukaryotic cells. Previously we found that its mechanism of action depends on membrane surface charge and on peptide-to-lipid ratio. Here we present the synthesis of two BP100 analogs: BP100­alanyl­hexadecyl­1­amine (BP100-Ala-NH-C16H33) and cyclo(1­4)­d­Cys1, Ile2, Leu3, Cys4-BP100 (Cyclo(1­4)­cILC-BP100). We examined their binding to large unilamellar vesicles (LUV), conformational and functional properties, and compared with those of BP100. The analogs bound to membranes with higher affinity and a lesser dependence on electrostatic forces than BP100. In the presence of LUV, BP100 and BP100-Ala-NH-C16H33 acquired α-helical conformation, while Cyclo(1­4)­cILC-BP100) was partly α-helical and partly ß-turn. Taking in conjunction: 1. particle sizes and zeta potential, 2. effects on lipid flip-flop, 3. leakage of LUVs internal contents, and 4. optical microscopy of giant unilamellar vesicles, we concluded that at high concentrations, all three peptides acted by a carpet mechanism, while at low concentrations the peptides acted by disorganizing the lipid bilayer, probably causing membrane thinning. The higher activity and lesser membrane surface charge dependence of the analogs was probably due to their greater hydrophobicity. The MIC values of both analogs towards Gram-positive and Gram-negative bacteria were similar to those of BP100 but both analogues were more hemolytic. Confocal microscopy showed Gram-positive B. subtilis killing with concomitant extensive membrane damage suggestive of lipid clustering, or peptide-lipid aggregation. These results were in agreement with those found in model membranes.

Alterações na formação do indivíduo na passagem do capitalismo liberal para o monopolista: o anacronismo da psicanálise freudiana à luz da teoria crítica da sociedade / Alterations in the individual's formation in the transition of liberal capitalism to monopoly capitalism: the anachronism of freudian psychoanalysis in the light of the critical theory of society / os cambios en la formación del individuo en el paso del capitalismo liberal al capitalismo monopolista: el anacronismo del psicoanálisis freudiano a la luz de la teoría crítica de la sociedad

Este artigo tem como referencial teórico a teoria crítica da sociedade proposta pela primeira geração da Escola de Frankfurt, especialmente as contribuições de T. W. Adorno e H. Marcuse, e tem como objetivo discutir as alterações da formação do indivíduo na passagem do capitalismo liberal para o monopolista. Para tanto, a psicanálise freudiana é utilizada como instrumento para ilustrar como as profundas mudanças econômicas, sociais e culturais impactaram a formação do indivíduo, apontando para a fragilização destes, levando ao favorecimento da adesão a movimentos de massas e totalitários. O anacronismo da psicanálise, portanto, não se refere ao envelhecimento dessa teoria, apesar de seus elementos ideológicos, mas para demonstrar o quanto o progresso se tornou em regressão nas transformações do capitalismo.

The theoretical framework of this paper is the critical theory of society proposed by the first generation of the Frankfurt School, especially the contributions of T. W. Adorno and H. Marcuse. It aims to discuss the changes in the formation of the individual in the transition of liberal capitalism into monopoly capitalism. Therefore, Freudian psychoanalysis is used as a tool to illustrate the way profound economic, social and cultural changes affected the formation of the individual pointing to their weakening, favoring the adhesion to movements of masses and totalitarianism. The anachronism of psychoanalysis, therefore, does not refer to the aging of this theory, despite its ideological elements, but it shows how progress has turned into regression in the capitalism transformations.

Este artículo tiene como referencial teórico la teoría crítica de la sociedad propuesta por la primera generación de la Escuela de Frankfurt, especialmente las contribuciones de T. W. Adorno y H. Marcuse y tiene como objetivo discutir los cambios en la formación del individuo en el paso del capitalismo liberal al monopolista. Para eso, el psicoanálisis freudiano se emplea como una herramienta para ilustrar cómo los profundos cambios económicos, sociales y culturales afectaron a la formación del individuo, señalando un debilitamiento de éstos, lo que lleva a lo favorecimiento de la adhesión a movimientos de masas y totalitarios. El anacronismo del psicoanálisis, por lo tanto, no se refiere al envejecimiento de esta teoría, a pesar de sus elementos ideológicos, sino a demostrar cuanto el progreso se convirtió en regresión en las transformaciones del capitalismo.

Adesão a movimentos totalitários e de massas: contribuições da teoria crítica da sociedade / Accession to totalitarian and masses movements: contributions of critical theory of society / Adhesión a los movimientos totalitarios y de masas: aportes de la teoría crítica de la sociedad

O artigo tem como referencial a Teoria Crítica da Sociedade nos moldes propostos por T. W. Adorno e H. Marcuse. Foram analisadas três obras de Freud com o objetivo de demonstrar como algumas contradições culturais tornam-se subjetividade na obra desse autor e como algumas de suas formulações antecipam os processos regressivos engendrados nos indivíduos pelo capitalismo monopolista, principalmente o fenômeno das massas. O conceito freudiano de ambivalência emocional serve de subsídio à compreensão da adesão de indivíduos a ideais que lhes seriam contrários. Assim, libido e agressividade são manejadas pela cultura visando à adesão das massas e coletividades. Adorno e Marcuse tomam a psicanálise como instrumento de análise da realidade social e a articulam com suas análises sobre o capitalismo em uma perspectiva marxiana.

The article has as reference the Critical Theory of the Society in the molds proposed by T. W. Adorno and H. Marcuse. Three works by Freud were analyzed in order to demonstrate how some cultural contradictions become subjectivity in the work of this author and how some of his formulations anticipate the regressive processes engendered in the individuals by the monopoly capitalism, mainly the phenomenon of the masses. The Freudian concept of emotional ambivalence serves as a basis for understanding the adherence of individuals to ideals that would be contrary to them. Thus, libido and aggressiveness are managed by the culture aiming to join the masses and collectivities. Adorno and Marcuse take psychoanalysis as an instrument of analysis of social reality and articulate it with their analysis of capitalism in a Marxian perspective.

El artículo tiene como referencial la Teoría Crítica de la Sociedad en los moldes propuestos por T. W. Adorno y H. Marcuse. En ello se analizaron tres obras de Freud con el objetivo de demostrar cómo algunas contradicciones culturales se tornan subjetividad en la obra de ese autor y como algunas de sus formulaciones anticipan los procesos regresivos engendrados en los individuos por el capitalismo monopolista, principalmente el fenómeno de las masas. El concepto freudiano de ambivalencia emocional sirve de subsidio a la comprensión de la adhesión de individuos a ideales que les serían contrarios. Así, libido y agresividad son manejadas por la cultura visando la adhesión de las masas y colectividades. Adorno y Marcuse toman el psicoanálisis como instrumento de análisis de la realidad social y la articulan con sus análisis sobre el capitalismo desde una perspectiva marxiana.

Peptoids successfully inhibit the growth of gram negative E. coli causing substantial membrane damage.

Peptoids are an alternative approach to antimicrobial peptides that offer higher stability towards enzymatic degradation. It is essential when developing new types of peptoids, that mimic the function of antimicrobial peptides, to understand their mechanism of action. Few studies on the specific mechanism of action of antimicrobial peptoids have been described in the literature, despite the plethora of studies on the mode of action of antimicrobial peptides. Here, we investigate the mechanism of action of two short cationic peptoids, rich in lysine and tryptophan side chain functionalities. We demonstrate that both peptoids are able to cause loss of viability in E. coli susceptible cells at their MIC (16-32 µg/ml) concentrations. Dye leakage assays demonstrate slow and low membrane permeabilization for peptoid 1, that is still higher for lipid compositions mimicking bacterial membranes than lipid compositions containing Cholesterol. At concentrations of 4 × MIC (64-128 µg/ml), pore formation, leakage of cytoplasmic content and filamentation were the most commonly observed morphological changes seen by SEM in E. coli treated with both peptoids. Flow cytometry data supports the increase of cell size as observed in the quantification analysis from the SEM images and suggests overall decrease of DNA per cell mass over time.

Apontamentos sobre a violência da cultura em Freud, Adorno e Marcuse / Notes on the violence of culture in Freud, Adorno and Marcuse / Notas sobre la violencia de la cultura en Freud, Adorno y Marcuse

O artigo tem como objetivo identificar como as categorias indivíduo e sociedade se relacionam em Freud, Adorno e Marcuse. Para tanto, foram analisadas três obras de Freud (Totem e tabu, 1913/1996; Psicologia das massas e análise do ego, 1921/1996, e Mal-estar na civilização, 1930/1996). Os resultados foram interpretados a partir das contribuições da Teoria Crítica da Sociedade proposta por Theodor W. Adorno e Herbert Marcuse. A cultura aparece como elemento importante na mediação da relação indivíduo e sociedade. Um dos aspectos que se destacou nas análises das obras freudianas foi a violência da cultura. As análises de Adorno e Marcuse aprofundam tal elemento ao inserir tal discussão nas reflexões acerca da sociedade capitalista. Um dos riscos de tal processo é a agressividade despertada por este, que pode se tornar destrutividade contra a cultura. Todavia, tais processos são manejados conscientemente e inconscientemente para manutenção do status quo.

The article aims to identify how the categories as individual and society are related in Freud, Adorno and Marcuse. Therefore, three works of Freud were analyzed (Totem and Taboo, 1913/1996; Psychology of the masses and the analysis of the ego, 1921/1996, and Civilization and its discontents, 1930/1996). The results were interpreted according to the contributions of the critical theory of society proposed by Theodor W. Adorno and Herbert Marcuse. The culture appears as important element in mediating the relationship individual and society. One of the important aspects highlighted in the analysis of Freudian works was the violence of the culture. The analyses of Adorno and Marcuse deepen such element inserting such discussion in the reflections of the capitalist society. One of the risks of such a process is the aggression generated by this process that can become violence against the culture. However, such processes are managed consciously and unconsciously to maintaining the status quo.

El artículo tiene como objetivo identificar cómo se relacionan categorías de individuo y sociedad de Freud, Adorno y Marcuse. Se seleccionaron y analizaron tres obras de Freud (Tótem y tabú, 1913/1996; Psicología de las masas y análisis del ego, 1921/1996, y Malestar en la civilización, 1930/1996). Os resultados fueron interpretados con las aportaciones de la teoría crítica de la sociedad propuesta por Theodor W. Adorno y Herbert Marcuse. La cultura aparece como elemento importante en la mediación de la relación individuo y sociedad. Uno de los elementos que se destacaron en el análisis de las obras freudianas fue la violencia de la cultura. El análisis de Adorno y Marcuse profundizan tal elemento para insertar este tipo de discusión en las reflexiones sobre la sociedad capitalista. Uno de los riesgos resultantes de dicho proceso es la agresividad que puede convertirse en destructividad contra cultura. Sin embargo, tales procesos son administrados conscientemente e inconscientemente para mantener el status quo.

Formação do indivíduo, capitalismo liberal e psicanálise: algumas contribuições daprimeira geração da escola de Frankfurt / Development of the Individual, Liberal Capitalism and Psychoanalysis: Contributions of the Frankfurt’sSchool First Generation

O presente artigo tem como referencial teórico a Teoria Crítica da Sociedade proposta pela primeira geração da Escola de Frankfurt, especialmente as contribuições de T. W. Adorno e H. Marcuse. Pretende-se discutir contribuições e contradições da psicanálise freudiana a partir da formação do indivíduo no capitalismo, como também, descrever a relação indivíduo e sociedade, dando prioridade às contradições do indivíduo liberal na perspectiva freudiana à luz da crítica da Escola de Frankfurt. Para tanto, foram tomadas como base do estudo três obras de Freud consideradas relevantes no que tange a relação indivíduo, sociedade e cultura. A psicanálise freudiana é apresentada a partir da sua defesa e crítica da ideologia liberal levando-se em consideração a perspectiva dos autores de referência. Destaca-se a importância da psicanálise como instrumento de crítica social, mesmo com seus aspectos ideológicos, pois esta, em suas próprias contradições, mantém a não identidade na relação indivíduo e sociedade fazendo ao mesmo tempo a defesa e a crítica da ideologia liberal e acentuando o caráter repressivo da civilização.(AU)

This article’s theoretical framework is the Frankfurt School’s Critical Theory focused on the contributions of T.W. Adorno and H. Marcuse. The article’s aim is to discuss contributions and contradictions of Freudian psychoanalytical views on individual development in capitalism. Three of Freud’s main essays that broach the relationship between the individual, society and culture are the basis of this work. Freudian psychoanalysis is presented in terms of its defense and criticism of liberal ideology and is considered to be a an instrument for social critique.(AU)

Formação do indivíduo, capitalismo liberal e psicanálise: algumas contribuições da primeira geração da escola de Frankfurt / Development of the Individual, Liberal Capitalism and Psychoanalysis: Contributions of the Frankfurt's School First Generation

O presente artigo tem como referencial teórico a Teoria Crítica da Sociedade proposta pela primeira geração da Escola de Frankfurt, especialmente as contribuições de T. W. Adorno e H. Marcuse. Pretende-se discutir contribuições e contradições da psicanálise freudiana a partir da formação do indivíduo no capitalismo, como também, descrever a relação indivíduo e sociedade, dando prioridade às contradições do indivíduo liberal na perspectiva freudiana à luz da crítica da Escola de Frankfurt. Para tanto, foram tomadas como base do estudo três obras de Freud consideradas relevantes no que tange a relação indivíduo, sociedade e cultura. A psicanálise freudiana é apresentada a partir da sua defesa e crítica da ideologia liberal levando-se em consideração a perspectiva dos autores de referência. Destaca-se a importância da psicanálise como instrumento de crítica social, mesmo com seus aspectos ideológicos, pois esta, em suas próprias contradições, mantém a não identidade na relação indivíduo e sociedade fazendo ao mesmo tempo a defesa e a crítica da ideologia liberal e acentuando o caráter repressivo da civilização.

This article's theoretical framework is the Frankfurt School's Critical Theory focused on the contributions of T.W. Adorno and H. Marcuse. The article's aim is to discuss contributions and contradictions of Freudian psychoanalytical views on individual development in capitalism. Three of Freud's main essays that broach the relationship between the individual, society and culture are the basis of this work. Freudian psychoanalysis is presented in terms of its defense and criticism of liberal ideology and is considered to be a an instrument for social critique.

Estudos biofísicos e de atividade de peptídeos correspondentes ao N-terminal das toxinas esticolisinais I e II - contribuição para a elucidação do mecanismo de ação / Biophysical and activity studies of peptides corresponding to the N-termini of sticholysins I and II - a contribution to the elucidation of the toxins' mechanism of action

Esticolisinas I e II, citolisinas purificadas da anêmona marinha Stichodactyla helianthus, agem lisando membranas biológicas e modelo. O mecanismo de ação proposto consiste na formação de um poro toroidal com o envolvimento do domínio N-terminal. Diferentes aspectos da interação entre peptídeos derivados do N-terminal das toxinas (StI1-31 and StI12-31 SELAGTIIDGASLTFEVLDKVLGELGKVSRK, e StII1-30 and StII11-30 ALAGTIIAGASLTFQVLDKVLEELGKVSRK) com membranas modelo - micelas e bicamadas - foram estudados com o objetivo de contribuir para a elucidação do mecanismo de ação das toxinas em nível molecular. O emprego dos peptídeos teve como base a hipótese de que fragmentos proteicos podem ser capazes de mimetizar a estrutura e atividade das proteínas inteiras. O análogo contendo o aminoácido paramagnético TOAC (N-TOAC-StII11-30) também foi estudado. Estudos conformacionais foram realizados empregando-se as técnicas espectroscópicas de dicroísmo circular (CD), ressonância paramagnética eletrônica (EPR) e fluorescência. Foram ainda realizados estudos de predição de estrutura e modelagem molecular. Espectros de CD mostraram que os peptídeos adquirem conformação em α-hélice ao interagir com membranas modelo, de acordo com a conformação observada nessa região para as toxinas. Variando a composição lipídica das membranas modelo estudadas, foi possível investigar a contribuição de forças eletrostáticas de de interações hidrofóbicas para a ligação do peptídeo. Ensaios de supressão de fluorescência de lípidos contendo grupamentos fluorescentes em diferentes posições pelo resíduo paramagnético TOAC e espectros de ressonância paramagnética eletrônica (EPR) permitiram localizar o resíduo TOAC na interface membrana-água, corroborando o modelo proposto do poro toroidal. A análise dos espectros de CD e EPR também permitiu obter as constantes de ligação dos peptídeos com micelas e bicamadas. Os peptídeos também foram capazes de mimetizar as toxinas do ponto de vista funcional, como mostrado por testes de vazamento de carboxifluoresceína e atividade hemolítica. Peptídeos curtos, contendo partes da sequência de StII1-30, sintetizados com o objetivo de examinar uma eventual atividade antimicrobiana, demonstraram baixa atividade, bem como ausência de atividade hemolítica e de toxicidade para células humanas

Sticholysins I and II, cytolysins purified from the sea anemone Stichodactyla helianthus, act by lysing biological and model membranes. The proposed mechanism of action consists in the formation of a toroidal pore with the involvement of the N-terminal domain [1]. Different aspects of the interaction between peptides from the toxins' N-termini (StI1-31 and StI12-31 SELAGTIIDGASLTFEVLDKVLGELGKVSRK, and StII1-30 and StII11-30 ALAGTIIAGASLTFQVLDKVLEELGKVSRK) and model membranes - micelles and bilayers - have been studied to contribute to the elucidation of the toxins mechanism of action at the molecular level. The use of peptides was based on the hypothesis that potein fragments can eventually mimic the structure and activity of the whole protein. An analogue containing the paramagnetic amino acid TOAC (N-TOAC-StII11-30) was also studied. Conformational studies were performed making use of the spectroscopic techniques circular dichroism (CD), electron paramagnetic resonance (EPR), and fluorescence. Studies of structure prediction and molecular modeling were also performed. CD spectra showed that the peptides acquired α-helical conformation upon interaction with model lipid membranes, in agreement with the conformation found for these segments in the whole proteins. Making use of membranes of variable lipid composition, it was possible to assess the contribution of electrostatic and hydrophobic interactions for peptide binding. Fluorescence quenching of labeled lipids by paramagnetic TOAC and EPR spectra allowed us to locate the TOAC residue at the membrane-water interface, corroborating the proposed model of the toroidal pore. The CD and EPR studies also allowed us to obtain the binding constants for the peptide-micelle and peptide-bilayer interaction. The peptides were also capable of mimicking the toxins function, as shown by assays of carboxyfluorescein leakage and hemolytic activity. Short peptides containing parts of StII1-30's sequence were synthesized with the aim of testing their antimicrobial activity. The peptides displayed low antimicrobial activity, as well as lack of hemolytic activity and toxicity against human cells