Uma abordagem problematizada em química experimental

Trabalho de Conclusão do Curso de Especialização em ensino de ciências e matemática para séries finais: Ensino Fundamental - 6o ao 9o ano da Universidade Federal da Integração Latino-Americana. Orientador: Prof. Dr. Márcio de Sousa Góes.O processo de ensino que envolve a disciplina de Química vem sendo discutido cada vez mais nos últimos anos visando torná-la mais atrativa aos alunos e aumentar, ao mesmo tempo, assimilação dos conteúdos contidos na Química. Atualmente é muito comum observar a falta de interesse e motivação dos alunos na disciplina, pois os alunos apresentam dificuldades em associar os conceitos apresentados porque estão condicionados a memorização dos conceitos e fórmulas. Para mudar este quadro, uma das vertentes é o uso de atividades experimentais de maneira frequente e habitual, pois a experimentação permite aos alunos associar o conteúdo teórico aliado à prática. Sendo assim, o presente trabalho tem como ponto central avaliar a influência da vivência da experimentação na aprendizagem de estudantes do 9o Ano do Ensino Fundamental II. Observou-se que a experimentação estimula o interesse dos alunos, por proporcionar a eles um contato direto com materiais que antes só faziam parte da sua imaginação.El proceso de enseñanza que implica la disciplina de Química, viene siendo discutido en los últimos años, con el objetivo de transformarla más atractiva para los alumnos y el aumento al mismo tiempo de la asimilación de los contenidos en Química. Actualmente es muy común ver la falta de interés y la motivación de los estudiantes en la disciplina porque los estudiantes tienen dificultad para asociar los conceptos presentados, ya que están condicionados a memorizar los conceptos y fórmulas. Para cambiar este cuadro, una cuestión a resaltar es el uso de actividades experimentales de manera frecuente y habitual, pues la experimentación permite a los alumnos asociar el contenido teórico aliado con la práctica. Por lo tanto, el presente trabajo tiene como punto central evaluar la influencia de la experiencia en el aprendizaje de los alumnos en el noveno año de la escuela primaria. Se observó que la experimentación estimula el interés de los alumnos, proporcionándoles un contacto directo con materiales que anteriormente formaban parte de su imaginación

Entwined dimer formation from self-complementary bis-acridiniums

International audienceThe self-assembling entwined dimer of a bis-acridinium tweezer has been investigated in organic and aqueous media. Please check this proof carefully. Our staff will not read it in detail after you have returned it. Please send your corrections either as a copy of the proof PDF with electronic notes attached or as a list of corrections. Do not edit the text within the PDF or send a revised manuscript as we will not be able to apply your corrections. Corrections at this stage should be minor and not involve extensive changes. Proof corrections must be returned as a single set of corrections, approved by all co-authors. No further corrections can be made after you have submitted your proof corrections as we will publish your article online as soon as possible after they are received. Please ensure that: The spelling and format of all author names and affiliations are checked carefully. You can check how we have identified the authors' first and last names in the researcher information table on the next page. Names will be indexed and cited as shown on the proof, so these must be correct

Combination of intact, middle-up and bottom-up levels to characterize 7 therapeutic monoclonal antibodies by capillary electrophoresis – Mass spectrometry

Significant growth of biopharmaceuticals requires powerful analytical methods to better understand their structure by establishing a complete characterization. To this end, a combination of bottom-up, middle-up and intact molecule levels with a capillary electrophoresis-mass spectrometry coupling has been performed to have a comprehensive picture of monoclonal antibodies. In this study, 7 worldwide health authorities approved mAbs have been analyzed to get information about their charge heterogeneity, the identification of post translational modifications (PTMs), their location and relative quantitation. Intact mAbs isoforms have been partially separated in less than 12 minutes and enabled to have a global illustration of mAbs heterogeneity and high masses PTMs characterization notably major N-glycosylation forms. Particularly, 2X-glycosylated and 1X-glycosylated forms have been partially separated. To deepen characterize PTMs carried by the backbone structure, advanced investigations at a middle-up level have been performed. Limited IdeS proteolysis allowed to study independently Fc/2 and F(ab)’2 fragments. Following the same separation conditions, isoforms of these fragments have been separated and data interpretation allowed to disclose additional PTMs as K-clip, oxidations or deamidations. A second intermediate level has been examined by adding a reduction step to establish a more precise assessment of PTMs and isoforms from the F(ab)’2 fragment. This reduction step released the light chains from the Fd fragment to get only 25 kDa fragments to analyze. CE-ESI-MS coupling allowed to get more information particularly about low masses PTMs. The precise location and relative quantitation of each PTM has been investigated at the peptidic level induced by a tryptic digestion of the studied mAbs. The concordance of the results shows the efficiency of the CE-ESI-MS coupling to characterize mAbs and highlight the need of the multi-level combination to get a comprehensive characterization of biotherapeutics

About thiol derivatization and resolution of basic proteins in two-dimensional electrophoresis.

web publisher www.interscience.wiley.comInternational audienceThe influence of thiol blocking on the resolution of basic proteins by two-dimensional electrophoresis was investigated. Cysteine blocking greatly increased resolution and decreased streaking, especially in the basic region of the gels. Two strategies for cysteine blocking were found to be efficient: classical alkylation with maleimide derivatives and mixed disulfide exchange with an excess of a low molecular weight disulfide. The effect on resolution was significant enough to allow correct resolution of basic proteins with in-gel rehydration on wide gradients (e.g. 3-10 and 4-12), but anodic cup-loading was still required for basic gradients (e.g. 6-12 or 8-12). These results demonstrate that thiol-related problems are not solely responsible for streaking of basic proteins on two-dimensional gels

QNESC: um estudo do estado da arte sobre as possibilidades de abordagens em química orgânica / QNESC: a state-of-the-art study on the possibilities of approaches in organic chemistry

RESUMOO presente artigo busca fazer uma pesquisa de estado da arte sobre tipos de abordagens desenvolvidas para Química orgânica. Para isso, foi realizada uma pesquisa de caráter bibliográfico descritivo, na Revista Química Nova na Escola (QNEsc) onde foram analisados 35 artigos publicados, no período de 2010 a 2018, que abordam a referida temática. O objetivo central foi verificar nas produções científicas as abordagens que facilitam o ensino e que podem subsidiar ferramentas e estratégias para professores, afim de melhorarem ou adaptarem seus trabalhos em sala de aula. O mapeamento dos trabalhos permitiu a classificação em categorias, tais como, abordagem CTS, temas geradores, experimentação, arte, projetos de trabalho, jogos, abordagens de modelos e analogias, histórico-cientificas e divulgação científica. Além disso, apresentou resultados expressivos considerando uma temática tão restrita dentro da química.

Structural characterization of antibody drug conjugate by a combination of intact, middle-up and bottom-up techniques using sheathless capillary electrophoresis – Tandem mass spectrometry as nanoESI infusion platform and separation method

Antibody-drug conjugates (ADCs) represent a fast growing class of biotherapeutic products. Their production leads to a distribution of species exhibiting different number of conjugated drugs overlaying the inherent com-plexity resulting from the monoclonal antibody format, such as glycoforms. ADCs require an additional level of characterization compared to first generation of biotherapeutics obtained through multiple analytical tech-niques for complete structure assessment. We report the development of complementary approaches imple-menting sheathless capillary electrophoresis-mass spectrometry (sheathless CE-MS) to characterize the differ-ent aspects defining the structure of brentuximab vedotin. Native MS using sheathless CE-MS instrument as a nanoESI infusion platform enabled accurate mass measurements and estimation of the average drug to anti-body ratio alongside to drug load distribution. Middle-up analysis performed after limited IdeS proteolysis allowed to study independently the light chain, Fab and F(ab’)2 subunits incorporating 1, 0 to 4 and 0 to 8 pay-loads respectively. Finally, a CZE-ESI-MS/MS methodology was developed in order to be compatible with hy-drophobic drug composing ADCs. From a single injection, complete sequence coverage could be achieved. Using the same dataset, glycosylation and drug-loaded peptides could be simultaneously identified revealing robust information regarding their respective localization and abundance. Drug-loaded peptide fragmentation mass spectra study demonstrated drug specific fragments reinforcing identification confidence, undescribed so far. Results reveal the method ability to characterize ADCs primary structure in a comprehensive manner while reducing tremendously the number of experiments required. Data generated showed that sheathless CZE-ESI-MS/MS characteristics position the methodology developed as a relevant alternative for comprehensive multi-level characterization of these complex biomolecule

Novel sheathless CE-MS interface as an original and powerful infusion platform for nanoESI study: from intact proteins to high molecular mass noncovalent complexes.:

Development of nano-electrospray (nanoESI) sources allowed to increase significantly the sensitivity which is often lacking when studying biological noncovalent assemblies. However, the flow rate used to infuse the sample into the mass spectrometer cannot be precisely controlled with nanoESI and the robustness of the system could represent an issue. In this study, we have used a sheathless capillary electrophoresis-mass spectrometry (CESI) prototype as a nanoESI infusion device. The hydrodynamic mobilization of the capillary content was characterized and the ability of the system to generate a stable electrospray under controlled flow rate conditions ranging from 4 up to 900 nL/min was demonstrated. The effect of the infusing flow rate on the detection of an intact model protein analyzed under native conditions was investigated. Results demonstrated a significant increase in sensitivity of 46-fold and a signal-to-noise ratio improvement of nearly 5-fold when using an infusing flow rate from 456.9 down to 13.7 nL/min. The CESI prototype was further used to detect successfully the β ring homodimer in its native conformation. Obtained results were compared with those achieved with conventional ESI. Intensity signals were increased by a factor of 5, while sample consumption decreased 80 times. β ring complexed with the P14 peptide was also studied. Finally, the CESI interface was used to observe the quaternary structure of native hemocyanins from Carcinus maenas crabs; this high molecular complex coexisting under various degrees of complexation and resulting in masses ranging from 445 kDa to 1.34 MD

Intact monoclonal antibodies separation and analysis by sheathless capillary electrophoresis-mass spectrometry

Capillary electrophoresis mass spectrometry coupling (CE-MS) is a growing technique in biopharmaceutics characterization. Assessment of monoclonal antibodies (mAbs) is well known at middle-up and bottom-up levels to obtain information about the sequence, post-translational modifications (PTMs) and degradation products. Intact protein analysis is an actual challenge to be closer to the real protein structure. At this level, actual techniques are time consuming or cumbersome processes. In this work, a 20 minutes separation method has been developed to optimize characterization of intact mAbs. Thus, separation have been done on a positively-charged coated capillary (PEI) with optimized volatile background electrolyte (BGE) and sample buffer (SB). A sheathless interface allowed to hyphenate CE to a quadrupole-time-of-flight mass spectrometer (Q-TOF) which parameters has been tuned to improve the high masses detection and identification of intact mAbs. Three world-wide health authorities approved mAbs have been used to set up a rapid and ease of use method. Intact trastuzumab, rituximab and palivizumab isoforms have been partially separated with this method in less than 20 minutes under denaturing conditions. For each mAb, 2X-glycosylated and 1X-glycosylated structures have been identified and separated. Concerning basic and acidic variants potential Iso-Asp modification and Asn deamidation have been observed. Accurate mass determination for high-mass molecular species remains a challenge, but the progress in intact mAbs separation appears very promising for biopharmaceutics characterization

Insights into metazoan evolution from <i>Alvinella pompejana</i> cDNAs

BackgroundAlvinella pompejana is a representative of Annelids, a key phylum for evo-devo studies that is still poorly studied at the sequence level. A. pompejana inhabits deep-sea hydrothermal vents and is currently known as one of the most thermotolerant Eukaryotes in marine environments, withstanding the largest known chemical and thermal ranges (from 5 to 105°C). This tube-dwelling worm forms dense colonies on the surface of hydrothermal chimneys and can withstand long periods of hypo/anoxia and long phases of exposure to hydrogen sulphides. A. pompejana specifically inhabits chimney walls of hydrothermal vents on the East Pacific Rise. To survive, Alvinella has developed numerous adaptations at the physiological and molecular levels, such as an increase in the thermostability of proteins and protein complexes. It represents an outstanding model organism for studying adaptation to harsh physicochemical conditions and for isolating stable macromolecules resistant to high temperatures.ResultsWe have constructed four full length enriched cDNA libraries to investigate the biology and evolution of this intriguing animal. Analysis of more than 75,000 high quality reads led to the identification of 15,858 transcripts and 9,221 putative protein sequences. Our annotation reveals a good coverage of most animal pathways and networks with a prevalence of transcripts involved in oxidative stress resistance, detoxification, anti-bacterial defence, and heat shock protection. Alvinella proteins seem to show a slow evolutionary rate and a higher similarity with proteins from Vertebrates compared to proteins from Arthropods or Nematodes. Their composition shows enrichment in positively charged amino acids that might contribute to their thermostability. The gene content of Alvinella reveals that an important pool of genes previously considered to be specific to Deuterostomes were in fact already present in the last common ancestor of the Bilaterian animals, but have been secondarily lost in model invertebrates. This pool is enriched in glycoproteins that play a key role in intercellular communication, hormonal regulation and immunity.ConclusionsOur study starts to unravel the gene content and sequence evolution of a deep-sea annelid, revealing key features in eukaryote adaptation to extreme environmental conditions and highlighting the proximity of Annelids and Vertebrates

Insights into metazoan evolution from Alvinella pompejana cDNAs.

International audienceBACKGROUND: Alvinella pompejana is a representative of Annelids, a key phylum for evo-devo studies that is still poorly studied at the sequence level. A. pompejana inhabits deep-sea hydrothermal vents and is currently known as one of the most thermotolerant Eukaryotes in marine environments, withstanding the largest known chemical and thermal ranges (from 5 to 105°C). This tube-dwelling worm forms dense colonies on the surface of hydrothermal chimneys and can withstand long periods of hypo/anoxia and long phases of exposure to hydrogen sulphides. A. pompejana specifically inhabits chimney walls of hydrothermal vents on the East Pacific Rise. To survive, Alvinella has developed numerous adaptations at the physiological and molecular levels, such as an increase in the thermostability of proteins and protein complexes. It represents an outstanding model organism for studying adaptation to harsh physicochemical conditions and for isolating stable macromolecules resistant to high temperatures. RESULTS: We have constructed four full length enriched cDNA libraries to investigate the biology and evolution of this intriguing animal. Analysis of more than 75,000 high quality reads led to the identification of 15,858 transcripts and 9,221 putative protein sequences. Our annotation reveals a good coverage of most animal pathways and networks with a prevalence of transcripts involved in oxidative stress resistance, detoxification, anti-bacterial defence, and heat shock protection. Alvinella proteins seem to show a slow evolutionary rate and a higher similarity with proteins from Vertebrates compared to proteins from Arthropods or Nematodes. Their composition shows enrichment in positively charged amino acids that might contribute to their thermostability. The gene content of Alvinella reveals that an important pool of genes previously considered to be specific to Deuterostomes were in fact already present in the last common ancestor of the Bilaterian animals, but have been secondarily lost in model invertebrates. This pool is enriched in glycoproteins that play a key role in intercellular communication, hormonal regulation and immunity. CONCLUSIONS: Our study starts to unravel the gene content and sequence evolution of a deep-sea annelid, revealing key features in eukaryote adaptation to extreme environmental conditions and highlighting the proximity of Annelids and Vertebrates