Browsing by Author "Calderón, Cristian"
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Publication Exploring the behavior of Candida antarctica lipase B in aqueous mixtures of an imidazolium ionic liquid and its surfactant analogue(2024) Campodónico, Paola; Calderón, Cristian; Alcázar, Jackson; Olivares, Belén; Jaldin, Limberg; Suárez, CristianThe performance of Candida antarctica lipase B (CALB) has been evaluated in 1- butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4)/water mixtures in a wide range of molar fractions (χBMIMBF4) with and without 1-dodecyl-3- methylimidazolium tetrafluoroborate (C12-MIMBF4), a surfactant derived from BMIMBF4. The main aim of this work is to evaluate the influence of χBMIMBF4 over micellar aggregates to assess the activity of enzymatic reactions. The investigated reaction corresponds to the hydrolysis of the substrate p-nitrophenyl laureate in each χBMIMBF4. The kinetic study for χBMIMBF4 at around 0.2 proved to be a border point in enzymatic activity. At χBMIMBF4 = 0.1, the lipase activity increases in thepresence of C12-MIMBF4. However, at higher concentrations, BMIMBF4 has a negligible effect over the lipase activity. These results suggest specific interactions between water and BMIMBF4 molecules in relation to CALB. This research highlights the superactivity phenomenon driven by the reaction media and the micelle interface. In this interfacial interaction, BMIMBF4 acts directly on the changes induced on the enzyme upon its interaction with the micellar interface. This study opens a green perspective toward the biocatalysis field.Item Solvent effect on a model SNAr reaction in ionic liquid/water mixtures at different compositions(2018) Calderón, Cristian; Garrido, Constanza; Sánchez, Bruno; Campodónico, PaolaThe reaction of phenyl 2,4,6-trinitrophenyl ether and piperidine was kinetically evaluated in BMIMBF4/ water mixtures as the reaction media. This study shows the dramatic effect of the mixture composition on the reacting pair and its reaction rate, highlighting two strongly demarcated zones. The first one, rich in water, is characterized by strong variations in the rate coefficient values, suggesting the presence of preferential solvent effects in the aqueous phase. The second zone shows high rate coefficient values independent of the composition of the solvent mixture, suggesting predominant ‘‘anion’’ solvent effects. These results were validated using fluorescence spectroscopy and the Kamlet–Taft parameter.Item Surfactant-mediated enzymatic superactivity in water/ionic liquid mixtures, evaluated on a model hydrolytic reaction catalyzed by α-chymotrypsin(Elsevier B.V., 2019-06) Calderón, Cristian; Contreras, Renato; Campodónico, PaolaIn this work, the influence of the C12-, C14-, and C16-alkyl chain derivatives of 1-alkyl-3-methyl-imidazole tetrafluoroborate over the hydrolisis of p-nitrophenyl trimethylacetate catalyzed by α-chymotrypsin was studied in water and water - ionic liquids mixtures. The ionic liquid used is 1-butyl-3-methyl-imidazole tetrafluoroborate (BMIMBF4). 1-alkyl-3-methylimidazole tetrafluoroborate derived surfactants can increase the catalytic efficiency of α-chymotrypsin on the hydrolysis of p-nitrophenyl trimethylacetate. This effect is negatively affected by the decrease on the surfactant's critical micelle concentration (CMC) and the partition of the substrate between the micelles and the external media observed above the critical miscellar concentration (CMC). In water/BMIMBF4 mixtures, the presence of the ionic liquid (IL), render the C14 and C16 surfactants insoluble, and overrides the effect elicited by the C12 alkyl chain surfactant on the activity of α-chymotrypsin. The loss of the surfactants influence on the enzymatic activity due to the presence of BMIMBF4 seems to be a complex process, controlled by a decreased affinity between α-chymotrypsin and the surfactant molecules and, to a larger extent, the appearance of an “acquired resistance” of the enzyme to the influence of the surfactants, related to a more compact and resilient conformation of the protein in the presence of BMIMBF4. The influence of BMIMBF4 is not only limited to the surfactant/enzyme interaction, but also it does modifies the partition of the substrate between the aqueous media and the micellar environment.