Electrochemical characterisation of Formate dehydrogenase and its catalytic properties

In recent years the amount of CO2 release into the planet atmosphere has increase exponentially due to a global dependency in fossil fuels. This is one of the major contributors to the climate change that is seen nowadays. On the other hand, due to the CO2 abundance, there has been an interest in developing methods to harvest and use this CO2 in the production of green energy and sustainable chemistry. Formate dehydrogenase (FDH) proteins are a class of metalloenzymes with different subunit composition containing either molybdenum or tungsten at the active site. FDH catalyses the oxidation of formate into CO2. Recently it was shown that some of the FDH enzymes have the ability to perform the reverse reaction that is, these can catalyse the reversible interconversion of CO2 and formate. However, to date, the electrochemical characterisation of the protein has not yet been attained using direct, non-mediated methods. In this thesis the isolation of FDH from Desulfovibrio desulfuricans, its biochemical and non-mediated electrochemical characterisation was attained. The redox features of the Mo catalytic centre of the enzyme, including thermodynamic and kinetic parameters such as its formal reduction potential (E0’ = -245 ± 8 mV vs NHE) and heterogeneous electron transfer constant, were determined, for the first time, using direct electrochemical methods. The catalytic activity towards the CO2 reduction was also observed, for the first time, by direct electrochemical techniques

Autoestima e satisfação de vida dos utilizadores da rede social instagram

As redes sociais têm evidenciado um crescimento exponencial na última década entre os jovens, com especial atenção para a rede social Instagram. Com esta crescente utilização torna-se crucial conhecer os efeitos da mesma na saúde mental dos seus utilizadores, nomeadamente ao nível do humor deprimido, comparação social, autoestima e satisfação de vida (Frison et al, 2017; Oliveira, 2014; Yeşilyurt et al., 2020). Esta investigação tem como principal objetivo analisar de que forma as características sociodemográficas, de utilização da rede social Instagram e a autoestima explicam a satisfação de vida dos utilizadores. O estudo foi constituído por 300 sujeitos de ambos os sexos, com idades entre os 18 e os 40 anos. Foi utilizado um questionário sociodemográfico, a escala de autoestima de Rosernbeg (versão portuguesa de Pechorro et al., 2011) e a escala de satisfação de vida (versão portuguesa de Simões 1991). Os resultados revelaram que existem diferenças significativas na autoestima em relação à idade dos sujeitos e número de seguidores no Instagram. Em relação à satisfação de vida, as horas de utilização da rede social e o número de seguidores mostraram diferenças significativas nesta variável. A autoestima revelou uma corrrelação significativa com a satisfação de vida, assim como um poder preditivo da mesma. Concluindo, as características de utilização da rede social Instagram influenciam a autoestima e satisfação de vida dos seus utilizadores e, a autoestima é um importante preditor de satisfação de vida, o que podem ser variáveis importantes a considerar em programas de sensibilização dos utilizadores em prol da sua saúde mental

Direct electrochemical reduction of carbon dioxide by a molybdenum-containing formate dehydrogenase

This work was supported by the Associate Laboratory for Green Chemistry -LAQV, with national funds from FCT/MCTES ( UID/QUI/50006/2019 ). LBM thanks to FCT/MCTES for the CEEC-Individual 2017 Program Contract.Formate dehydrogenase enzymes catalyse the reversible two-electron oxidation of formate to carbon dioxide. The class of metal-dependent formate dehydrogenases comprises prokaryotic enzymes holding redox-active centres and a catalytic site, containing either molybdenum or tungsten ion, that mediates the formate/carbon dioxide interconversion. The carbon dioxide reduction is of a particular interest, since it may be a route for its atmospheric mitigation with the simultaneous production of added-value products, as formate-derived compounds. Recently, the periplasmic formate dehydrogenase from Desulfovibrio desulfuricans, a molybdenum-containing enzyme, was proven to be an efficient enzyme for the CO 2 reduction to formate. In this work, the immobilized formate dehydrogenase isolated from Desulfovibrio desulfuricans direct electrochemical behaviour was attained in the presence and absence of substrates and the formal potentials associated with the catalytic centre transitions were determined in non-turnover conditions. The enzyme catalytic activity towards carbon dioxide reduction was observed using direct electrochemical methods.authorsversionpublishe