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Unveiling the Three-Step Model for the Interaction of Imidazolium-Based Ionic Liquids on Albumin

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Autor(es):
Raw, Juliana ; Franco, Leandro R. ; de C. Rodrigues, Luiz Fernando ; Barbosa, Leandro R. S.
Número total de Autores: 4
Tipo de documento: Artigo Científico
Fonte: ACS OMEGA; v. 8, n. 41, p. 10-pg., 2023-10-05.
Resumo

The effect of the ionic liquids (ILs) 1-methyl-3-tetradecylimidazolium chloride ([C14MIM][Cl]), 1-dodecyl-3-methylimidazolium chloride ([C12MIM][Cl]), and 1-decyl-methylimidazolium chloride ([C10MIM][Cl]) on the structure of bovine serum albumin (BSA) was investigated by fluorescence spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, small-angle X-ray scattering (SAXS), and molecular dynamics (MD) simulations. Concerning the fluorescence measurements, we observed a blue shift and a fluorescence quenching as the IL concentration increased in the solution. Such behavior was observed for all three studied imidazolium-based ILs, being larger as the number of methylene groups in the alkyl chain increased. UV-vis absorbance measurements indicate that even at relatively small IL/protein ratios, like 1:1 or 1:2, ([C14MIM][Cl]) is able to change, at least partially, the sample turbidity. SAXS results agree with the spectroscopic techniques and suggest that the proteins underwent partial unfolding, evidenced by an increase in the radius of gyration (R-g) of the scattering particle. In the absence and presence of ([C14MIM][Cl]) = 3 mM BSA R-g increases from 29.1 to 45.1 & Aring;, respectively. Together, these results indicate that the interaction of BSA with ILs is divided into three stages: the first stage is characterized by the protein in its native form. It takes place for protein/IL <= 1:2, and the interaction is predominantly due to the electrostatic forces provided by the negative charges on the surface of BSA and the cationic polar head of the ILs. In the second stage, higher IL concentrations induce the unfolding of the protein, most likely inducing the unfolding of domains I and III, in such a way that the protein's secondary structure is kept almost unaltered. In the last stage, IL micelles start to form, and therefore, the interaction with protein reaches a saturation point and free micelles may be formed. We believe that this work provides new information about the interaction of ILs with BSA. (AU)

Processo FAPESP: 16/05019-0 - A influência termodinâmica e estrutural de líquidos iônicos em sistemas biomiméticos de membrana
Beneficiário:Natália Fernandes de Oliveira
Modalidade de apoio: Bolsas no Brasil - Iniciação Científica
Processo FAPESP: 17/26131-5 - Chaperoma: estudo da relação entre a estrutura dos seus componentes e a manutenção da proteostase
Beneficiário:Carlos Henrique Inacio Ramos
Modalidade de apoio: Auxílio à Pesquisa - Temático
Processo FAPESP: 15/15822-1 - Estudo das propriedades físico-químicas e estruturais de fármacos e líquidos iônicos com sistemas de relevância biológica
Beneficiário:Leandro Ramos Souza Barbosa
Modalidade de apoio: Auxílio à Pesquisa - Regular