Ultraviolet–circular dichroism spectroscopy and potentiometric study of the interaction between human serum albumin and sodium perfluorooctanoate

Authors

  • Paula Messina,

    1. Grupo de Ciencia de Superficies y Coloides, Departamento de Química, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina
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  • Gerardo Prieto,

    Corresponding author
    1. Grupo de Biofísica e Interfases, Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
    • Grupo de Biofísica e Interfases, Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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  • Verónica Dodero,

    1. Departamento de Química Orgánica, Facultad de Química, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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  • Juan M. Ruso,

    1. Grupo de Ciencia de Superficies y Coloides, Departamento de Química, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina
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  • Pablo Schulz,

    1. Grupo de Ciencia de Superficies y Coloides, Departamento de Química, Universidad Nacional del Sur, 8000 Bahía Blanca, Argentina
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  • Félix Sarmiento

    1. Grupo de Biofísica e Interfases, Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Abstract

The interaction of a fluorinated surfactant, sodium perfluorooctanoate, with human serum albumin (HSA) has been investigated by a combination of ultraviolet–circular dichroism (UV-CD) spectroscopy and potentiometry (by a home-built ion-selective electrode) techniques to detect and characterize the conformational transitions of HSA. By using difference spectroscopy, the transition was followed as a function of temperature, and the data were analyzed to obtain the parameters characterizing the thermodynamics of unfolding. The results indicate that the presence of surfactant drastically changes the melting unfolding, acting as a structure stabilizer and delaying the unfolding process. Potentiometric measurements were used to determine the binding isotherms and binding capacity for this system. The isotherm shows a high affinity of surfactant molecules for HSA. The average number of surfactant molecules absorbed per protein molecule (at 28 mM of surfactant concentration) was found to be ≈900, about 6 g of surfactant per gram of protein. The shape of the binding capacity curve and the relation between binding capacity and extend of cooperativity were examined. From these analysis, the values of g (number of ligand-binding sites), KH (Hill binding constant), and nH (Hill coefficient) were determined. © 2005 Wiley Periodicals, Inc. Biopoly 79: 300–309, 2005

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

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