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Advisor(s)
Abstract(s)
Os efeitos específicos de iões na solubilidade de biomoléculas em soluções aquosas
assumem um papel muito importante nas ciências da vida e na biotecnologia.
O presente trabalho pretende contribuir para o estudo do efeito da presença de sais inorgânicos
na solubilidade de péptidos em soluções aquosas. Para isso, foram selecionados
dois compostos modelo derivados do aminoácido glicina: diglicina e N-acetilglicina.
Para a medição experimental da solubilidade, aplicou-se o método analítico isotérmico,
à temperatura de 298,15 K, efetuando-se a análise da composição das soluções saturadas
por gravimetria (sais anidros) ou por medição do índice de refração (sais hidratados).
Foram estudados os sais anidros cloreto de amónio, cloreto de potássio, cloreto de sódio,
sulfato de amónio, sulfato de potássio e sulfato de sódio e, também, os sais hidratados
cloreto de cálcio, cloreto de magnésio e sulfato de magnésio.
Relativamente aos resultados obtidos verificou-se, em geral, a diminuição da solubilidade
da N-acetilglicina e o aumento da solubilidade da diglicina, com o aumento da
concentração dos sais em estudo. Os sais dos catiões divalentes foram aqueles que induziram
um maior efeito de “salting-in” na solubilidade da diglicina, em particular o cloreto
de cálcio. Por outro lado, os sais sulfato de magnésio e sulfato de sódio induziram o
maior efeito de “salting-out” na N-acetilglicina. A informação experimental disponível
na literatura sobre estes sistemas é muito reduzida. No entanto, nos casos em que foi
possível efetuar uma comparação, verificou-se elevada consistência entre os dados medidos
neste trabalho e os de outros autores.
Por fim, será importante avaliar o efeito do pH na solubilidade destes compostos bem
como efetuar estudos adicionais de dinâmica molecular para suportar a interpretação
dos resultados experimentais apresentados neste trabalho.
The specific ion effects on the solubility of biomolecules in aqueous solutions play a very important role in the life sciences and biotechnology. This work aims to contribute to the study of the effect of inorganic salts on the solubility of peptides in aqueous solutions. To this purpose, two model compounds derived from glycine were selected: diglycine and N-acetylglycine. The solubility was measured by applying the isothermal analytical method, at a temperature of 298.15 K, in which the analysis of the composition of the saturated solutions was performed by gravimetry (anhydrous salts) or by measuring the refractive index (hydrated salts). The anhydrous salts ammonium chloride, potassium chloride, sodium chloride, ammonium sulfate, potassium sulfate and sodium sulfate were studied, and also, the hydrated salts calcium chloride, magnesium chloride and magnesium sulfate. Regarding the results obtained, it was found that, in general, by increasing the concentration of the salts, the solubility of N-acetylglycine decreased and the solubility of diglycine increased. Salts of the divalent cations induced a greater "salting-in" effect on the solubility of diglycine, in particular, calcium chloride. On the other hand, magnesium sulfate and sodium sulfate induced the largest "salting-out" effect on Nacetylglycine. The experimental data available in the literature on these systems are scarce. However, in cases where a comparison was possible, there is high consistency between the data measured in this work and by other authors. Finally, it would be important to evaluate the pH effect on the solubility of these compounds and to perform further molecular dynamics studies to support the interpretation of the experimental results presented in this work.
The specific ion effects on the solubility of biomolecules in aqueous solutions play a very important role in the life sciences and biotechnology. This work aims to contribute to the study of the effect of inorganic salts on the solubility of peptides in aqueous solutions. To this purpose, two model compounds derived from glycine were selected: diglycine and N-acetylglycine. The solubility was measured by applying the isothermal analytical method, at a temperature of 298.15 K, in which the analysis of the composition of the saturated solutions was performed by gravimetry (anhydrous salts) or by measuring the refractive index (hydrated salts). The anhydrous salts ammonium chloride, potassium chloride, sodium chloride, ammonium sulfate, potassium sulfate and sodium sulfate were studied, and also, the hydrated salts calcium chloride, magnesium chloride and magnesium sulfate. Regarding the results obtained, it was found that, in general, by increasing the concentration of the salts, the solubility of N-acetylglycine decreased and the solubility of diglycine increased. Salts of the divalent cations induced a greater "salting-in" effect on the solubility of diglycine, in particular, calcium chloride. On the other hand, magnesium sulfate and sodium sulfate induced the largest "salting-out" effect on Nacetylglycine. The experimental data available in the literature on these systems are scarce. However, in cases where a comparison was possible, there is high consistency between the data measured in this work and by other authors. Finally, it would be important to evaluate the pH effect on the solubility of these compounds and to perform further molecular dynamics studies to support the interpretation of the experimental results presented in this work.
Description
Keywords
N-acetilglicina Diglicina Sais Solubilidade