Centro de Ciências Exatas e Tecnológicas
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/9791
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5 resultados
Resultados da Pesquisa
Item Determination of driving forces for bovine serum albumin-Ponceau4R binding using surface plasmon resonance and fluorescence spectroscopy: A comparative study(Food Hydrocolloids, 2017-09) Lelis, Carini Aparecida; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Hespanhol, Maria do Carmo; Pinto, Maximiliano Soares; Silva, Luis Henrique Mendes da; Pires, Ana Clarissa dos SantosPonceau 4R (P4R) and bovine serum albumin (BSA) may interact changing food properties. We compared fluorescence spectroscopy and surface plasmon resonance (SPR) for studying, in vitro, the interactions between BSA and P4R at pH 7.4 and 3.5 in different temperatures. Fluorescence data pointed to the formation of a complex where P4R was bound on site I or II of BSA, with a stoichiometry around one and a binding constant (Kb) ranging from 1.37 × 105 to 20.15 × 106 L mol−1. The complex formation at both pH was enthalpically driven (standard enthalpy change, ΔH°F = −60.69 and −63.06 kJ mol−1, for pH 7.4 and 3.5, respectively). Using SPR, we also found the formation of 1:1 BSA-P4R complexes, but the calculated Kb values were much smaller, on the order of 103 L mol−1. Again, we found that the formation of BSA-P4R complex was driven by enthalpy decreasing; however the standard enthalpy change was less negative than that found by fluorescence (ΔH°SPR = −15.05 and −40.55 kJ mol−1, at pH 7.4 and 3.5, respectively). Our results show that these distinct techniques provided different thermodynamic binding parameters for the BSA-P4R interaction, especially regarding ΔH° values, indicating that BSA-P4R binding was a multisite phenomenon, and that sites far from tryptophan residues were the main responsible by electrostatic interaction. Thus, this work clearly shows the importance of using complementary techniques for a complete thermodynamic characterization of complexes formed between azo-colorants and proteins; which is directly related to physicochemical properties of systems containing both molecules together.Item Determination of driving forces for bovine serum albumin-Ponceau4R binding using surface plasmon resonance and fluorescence spectroscopy: a comparative study(Food Hydrocolloids, 2017-09) Lelis, Carini Aparecida; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Hespanhol, Maria do Carmo; Pinto, Maximiliano Soares; Silva, Luis Henrique Mendes da; Pires, Ana Clarissa dos SantosPonceau 4R (P4R) and bovine serum albumin (BSA) may interact changing food properties. We compared fluorescence spectroscopy and surface plasmon resonance (SPR) for studying, in vitro, the interactions between BSA and P4R at pH 7.4 and 3.5 in different temperatures. Fluorescence data pointed to the formation of a complex where P4R was bound on site I or II of BSA, with a stoichiometry around one and a binding constant (Kb) ranging from 1.37 × 10^5 to 20.15 × 10^6 L mol^−1. The complex formation at both pH was enthalpically driven (standard enthalpy change, ΔH°F = −60.69 and −63.06 kJ mol^−1, for pH 7.4 and 3.5, respectively). Using SPR, we also found the formation of 1:1 BSA-P4R complexes, but the calculated Kb values were much smaller, on the order of 103 L mol^−1. Again, we found that the formation of BSA-P4R complex was driven by enthalpy decreasing; however the standard enthalpy change was less negative than that found by fluorescence (ΔH°SPR = −15.05 and −40.55 kJ mol^−1, at pH 7.4 and 3.5, respectively). Our results show that these distinct techniques provided different thermodynamic binding parameters for the BSA-P4R interaction, especially regarding ΔH° values, indicating that BSA-P4R binding was a multisite phenomenon, and that sites far from tryptophan residues were the main responsible by electrostatic interaction. Thus, this work clearly shows the importance of using complementary techniques for a complete thermodynamic characterization of complexes formed between azo-colorants and proteins; which is directly related to physicochemical properties of systems containing both molecules together.Item Binding thermodynamics of synthetic dye Allura Red with bovine serum albumin(Food Chemistry, 2017-02-15) Lelis, Carini Aparecida; Hudson, Eliara Acipreste; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Silva, Luis Henrique Mendes da; Silva, Maria do Carmo Hespanhol da; Pinto, Maximiliano Soares; Pires, Ana Clarissa dos SantosThe interaction between Allura Red and bovine serum albumin (BSA) was studied in vitro at pH 7.4. The fluorescence quenching was classified as static quenching due to the formation of AR–BSA complex, with binding constant (K) ranging from 3.26 ± 0.09 to 8.08 ± 0.06 104 L.mol−1, at the warfarin binding site of BSA. This complex formation was driven by increasing entropy. Isothermal titration calorimetric measurements also showed an enthalpic contribution. The Allura Red diffusion coefficient determined by the Taylor-Aris technique corroborated these results because it reduced with increasing BSA concentration. Interfacial tension measurements showed that the AR–BSA complex presented surface activity, since interfacial tension of the water-air interface decreased as the colorant concentration increased. This technique also provided a complexation stoichiometry similar to those obtained by fluorimetric experiments. This work contributes to the knowledge of interactions between BSA and azo colorants under physiological conditions.Item Kinetics and thermodynamics of bovine serum albumin interactions with Congo red dye(Colloids and Surfaces B: Biointerfaces, 2017-08-24) Paula, Hauster Maximiler Campos de; Coelho, Yara Luiza; Agudelo, Alvaro Javier Patiño; Rezende, Jaqueline de Paula; Ferreira, Gabriel Max Dias; Ferreira, Guilherme Max Dias; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes daTo optimize the therapeutic applications of Congo red (CR), a potential inhibitor of protein aggregation, the kinetics and thermodynamics of the interactions between CR and a model protein need to be understood. We used surface plasmon resonance (SPR) and fluorescence techniques to determine the dynamics and thermodynamic parameters for the formation of complexes between CR and bovine serum albumin (BSA). CR interacts with BSA through a transition complex; the activation energy for association (Eact(a)) was determined to be 35.88 kJ mol−1, while the activation enthalpy (ΔH‡), entropy (ΔS‡), and Gibbs free energy (ΔG‡) are 33.41 kJ mol−1, 0.18 J mol−1 K−1, and 33.35 kJ mol−1, respectively. When this intermediate transforms into the final CR-BSA complex, the entropy of the system increases and part of the absorbed energy is released; this process is associated with a reverse activation energy (Eact(d)) of 20.17 kJ mol−1, and values of ΔH‡, ΔS‡, and ΔG‡ of 17.69 kJ mol−1, −162.86 J mol−1 K−1, and 66.25 kJ mol−1, respectively. A comparison of the SPR and fluorescence results suggests that there is more than one site where BSA interacts with CR.Item Polydiacetylene/triblock copolymer nanosensor for the detection of native and free bovine serum albumin(Materials Science and Engineering: C, 2017-01-01) Rezende, Jaqueline de Paula; Ferreira, Guilherme Max Dias; Ferreira, Gabriel Max Dias; Silva, Luis Henrique Mendes da; Silva, Maria do Carmo Hepanhol da; Pinto, Maximiliano Soares; Pires, Ana Clarissa dos SantosBovine serum albumin (BSA) has been recognized as a marker of the cow's health, milk quality, an allergenic protein and as a carrier. Its detection is important in the food, pharmaceutical and medical industries. However, traditional techniques used to detect BSA are often time-consuming, expensive, and show limited sensitivity. This paper describes properties of polydiacetylene-triblock copolymer (L64) nanosensors, synthesized to easily detect BSA. Sensor efficiency was studied as a function of nanosensor composition, polydiacetylene chemical structures, BSA conformation and hydrophobic domain availability, using spectroscopic, calorimetric, light scattering, and electrokinetic analyses. Nanosensors were sensitive to detect the average BSA concentration of milk and dairy products and discriminated between native and denatured protein through naked-eye detectable blue-to-red transition. The standard Gibbs free energy (− 10.44 < ΔG° < − 49.52 kJ M), stoichiometry complex (1 < “n” < 3), and binding constant (6.7 × 10^2 < Ka < 4.79 × 10^8 M^− 1) of BSA-nanosensor complex formation established a direct relationship between nanosensor response and BSA-nanosensor interaction. BSA-nanosensor interaction was entropically (without cholesterol), and enthalpically driven (with cholesterol). Eugenol-BSA complex did not induce colorimetric transition. Polydiacetylene-L64 nanosensors are potential low-cost sensors for rapid detection of BSA, discriminating between native/denatured and free/bound protein.