Contribuições das Histórias em Quadrinhos para abordar questões ambientais na educação básica

O presente estudo refere-se à construção do conhecimento de forma coletiva a partir da elaboração de material didático através das histórias em quadrinhos. Por se tratar de um veículo de massa com fácil entendimento, seu conteúdo pode ser trabalhado em diferentes seguimentos contextualizando temas, tais como meio ambiente, nas aulas de ciências através de uma linguagem que une o texto à imagem proporcionando ao professor levar o aluno a refletir sobre questões que possam estar associadas ao seu cotidiano. As atividades seguiram uma sequência didática estruturada que envolveu pesquisa sobre questões ambientais, debate acerca da opinião dos alunos em relação as informações que obtiveram em suas pesquisas, dicas de como criar histórias em quadrinhos, a elaboração dos quadrinhos e discussões relacionadas à leitura dessas hitórias produzidas pelos alunos. Desta forma o conhecimento construído coletivamente através das atividades contribuiu para o desenvolvimento da argumentação dos alunos, a crítica de forma reflexiva, o hábito de leitura e para a organização do trabalho em equipe

Surface-exposed Tryptophan Residues Are Essential for O-Acetylserine Sulfhydrylase Structure, Function, and Stability

O-Acetylserine sulfhydrylase is a homodimeric enzyme catalyzing the last step of cysteine biosynthesis via a Bi Bi ping-pong mechanism. The subunit is composed of two domains, each containing one tryptophan residue, Trp50 in the N-terminal domain and Trp161 in the C-terminal domain. Only Trp161 is highly conserved in eucaryotes and bacteria. The coenzyme pyridoxal 5'-phosphate is bound in a cleft between the two domains. The enzyme undergoes an open to closed conformational transition upon substrate binding. The effect of single Trp to Tyr mutations on O-acetylserine sulfhydrylase structure, function, and stability was investigated with a variety of spectroscopic techniques. The mutations do not significantly alter the enzyme secondary structure but affect the catalysis, with a predominant influence on the second half reaction. The W50Y mutation strongly affects the unfolding pathway due to the destabilization of the intersubunit interface. The W161Y mutation, occurring in the C-terminal domain, produces a reduction of the accessibility of the active site to acrylamide and stabilizes thermodynamically the N-terminal domain, a result consistent with stronger interdomain interactions

Photoinduced Millisecond Switching Kinetics in the GFPMut2 E222Q Mutant

n/

Discovery of novel fragments inhibiting O-acetylserine sulphhydrylase by combining scaffold hopping and ligand-based drug design.

Several bacteria rely on the reductive sulphur assimilation pathway, absent in mammals, to synthesise cysteine. Reduction of virulence and decrease in antibiotic resistance have already been associated with mutations on the genes that codify cysteine biosynthetic enzymes. Therefore, inhibition of cysteine biosynthesis has emerged as a promising strategy to find new potential agents for the treatment of bacterial infection. Following our previous efforts to explore OASS inhibition and to expand and diversify our library, a scaffold hopping approach was carried out, with the aim of identifying a novel fragment for further development. This novel chemical tool, endowed with favourable pharmacological characteristics, was successfully developed, and a preliminary Structure-Activity Relationship investigation was carried out

Interaction of human hemoglobin and semi-hemoglobins with the Staphylococcus aureus hemophore IsdB: a kinetic and mechanistic insight

Among multidrug-resistant bacteria, methicillin-resistant Staphylococcus aureus is emerging as one of the most threatening pathogens. S. aureus exploits different mechanisms for its iron supply, but the preferred one is acquisition of organic iron through the expression of hemoglobin (Hb) receptors. One of these, IsdB, belonging to the Isd (Iron-Regulated Surface Determinant) system, was shown to be essential for bacterial growth and virulence. Therefore, interaction of IsdB with Hb represents a promising target for the rational design of a new class of antibacterial molecules. However, despite recent investigations, many structural and mechanistic details of complex formation and heme extraction process are still elusive. By combining site-directed mutagenesis, absorption spectroscopy, surface plasmon resonance and molecular dynamics simulations, we tackled most of the so far unanswered questions: (i) the exact complex stoichiometry, (ii) the microscopic kinetic rates of complex formation, (iii) the IsdB selectivity for binding to, and extracting heme from, α and β subunits of Hb, iv) the role of specific amino acid residues and structural regions in driving complex formation and heme transfer, and (v) the structural/dynamic effect played by the hemophore on Hb

Discovery of Substituted (2-Aminooxazol-4-yl)Isoxazole-3-carboxylic Acids as Inhibitors of Bacterial Serine Acetyltransferase in the Quest for Novel Potential Antibacterial Adjuvants

Many bacteria and actinomycetales use L-cysteine biosynthesis to increase their tolerance to antibacterial treatment and establish a long-lasting infection. In turn, this might lead to the onset of antimicrobial resistance that currently represents one of the most menacing threats to public health worldwide. The biosynthetic machinery required to synthesise L-cysteine is absent in mammals; therefore, its exploitation as a drug target is particularly promising. In this article, we report a series of inhibitors of Salmonella thyphimurium serine acetyltransferase (SAT), the enzyme that catalyzes the rate-limiting step of L-cysteine biosynthesis. The development of such inhibitors started with the virtual screening of an in-house library of compounds that led to the selection of seven structurally unrelated hit derivatives. A set of molecules structurally related to hit compound 5, coming either from the original library or from medicinal chemistry efforts, were tested to determine a preliminary structure–activity relationship and, especially, to improve the inhibitory potency of the derivatives, that was indeed ameliorated by several folds compared to hit compound 5 Despite these progresses, at this stage, the most promising compound failed to interfere with bacterial growth when tested on a Gram-negative model organism, anticipating the need for further research efforts

Discovery of Substituted (2-Aminooxazol-4-yl)Isoxazole-3-carboxylic Acids as Inhibitors of Bacterial Serine Acetyltransferase in the Quest for Novel Potential Antibacterial Adjuvants

Many bacteria and actinomycetales use L-cysteine biosynthesis to increase their tolerance to antibacterial treatment and establish a long-lasting infection. In turn, this might lead to the onset of antimicrobial resistance that currently represents one of the most menacing threats to public health worldwide. The biosynthetic machinery required to synthesise L-cysteine is absent in mammals; therefore, its exploitation as a drug target is particularly promising. In this article, we report a series of inhibitors of Salmonella thyphimurium serine acetyltransferase (SAT), the enzyme that catalyzes the rate-limiting step of L-cysteine biosynthesis. The development of such inhibitors started with the virtual screening of an in-house library of compounds that led to the selection of seven structurally unrelated hit derivatives. A set of molecules structurally related to hit compound 5, coming either from the original library or from medicinal chemistry efforts, were tested to determine a preliminary structure–activity relationship and, especially, to improve the inhibitory potency of the derivatives, that was indeed ameliorated by several folds compared to hit compound 5 Despite these progresses, at this stage, the most promising compound failed to interfere with bacterial growth when tested on a Gram-negative model organism, anticipating the need for further research efforts

The Energy Landscape of Human Serine Racemase

Human serine racemase is a pyridoxal 5′-phosphate (PLP)-dependent dimeric enzyme that catalyzes the reversible racemization of L-serine and D-serine and their dehydration to pyruvate and ammonia. As D-serine is the co-agonist of the N-methyl-D-aspartate receptors for glutamate, the most abundant excitatory neurotransmitter in the brain, the structure, dynamics, function, regulation and cellular localization of serine racemase have been investigated in detail. Serine racemase belongs to the fold-type II of the PLP-dependent enzyme family and structural models from several orthologs are available. The comparison of structures of serine racemase co-crystallized with or without ligands indicates the presence of at least one open and one closed conformation, suggesting that conformational flexibility plays a relevant role in enzyme regulation. ATP, Mg2+, Ca2+, anions, NADH and protein interactors, as well as the post-translational modifications nitrosylation and phosphorylation, finely tune the racemase and dehydratase activities and their relative reaction rates. Further information on serine racemase structure and dynamics resulted from the search for inhibitors with potential therapeutic applications. The cumulative knowledge on human serine racemase allowed obtaining insights into its conformational landscape and into the mechanisms of cross-talk between the effector binding sites and the active site

Therapeutic alternatives in chronic thromboembolic pulmonary hypertension: from pulmonary endarterectomy to balloon pulmonary angioplasty to medical therapy. State of the art from a multidisciplinary team

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease with a very complex pathophysiology differing from other causes of pulmonary hypertension (PH). It is an infrequent consequence of acute pulmonary embolism that is frequently misdiagnosed. Pathogenesis has been related to coagulation abnormalities, infection or inflammation, although these disturbances can be absent in many cases. The hallmarks of CTEPH are thrombotic occlusion of pulmonary vessels, variable degree of ventricular dysfunction and secondary microvascular arteriopathy. The definition of CTEPH also includes an increase in mean pulmonary arterial pressure of more than 25 mmHg with a normal pulmonary capillary wedge of less than 15 mmHg. It is classified as World Health Organization group 4 PH, and is the only type that can be surgically cured by pulmonary endarterectomy (PEA). This operation needs to be carried out by a team with strong expertise, from the diagnostic and decisional pathway to the operation itself. However, because the disease has a very heterogeneous phenotype in terms of anatomy, degree of PH and the lack of a standard patient profile, not all cases of CTEPH can be treated by PEA. As a result, PH-directed medical therapy traditionally used for the other types of PH has been proposed and is utilized in CTEPH patients. Since 2015, we have been witnessing the rebirth of balloon pulmonary angioplasty, a technique first performed in 2001 but has since fallen out fashion due to major complications. The refinement of such techniques has allowed its safe utilization as a salvage therapy in inoperable patients. In the present keynote lecture, we will describe these therapeutic approaches and results