European Biophysics Journal

, Volume 30, Issue 4, pp 242–249 | Cite as

Secondary structure of prothymosin α evidenced for conformational transitions induced by changes in temperature and concentration of n-dodecyltrimethylammonium bromide

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Article

Abstract.

Conformational changes of prothymosin α (ProTα) induced by changes in temperature and concentration of the denaturant n-dodecyltrimethylammonium bromide (C12TAB) were studied by difference spectroscopy. The conformational transition of ProTα by C12TAB was followed as a function of denaturant concentration by absorbance measurements at 230 nm and the data were analyzed to obtain the Gibbs energy of the transition in water \( \left( {\Delta G_{\rm w}^0 } \right) \) and in a hydrophobic environment \( \left( {\Delta G_{{\rm hc}}^0 } \right) \) for saturated protein-surfactant complexes. The value of \( \Delta G_{\rm w}^0 \) was 6.38 kJ mol–1 and that for \( \Delta G_{{\rm hc}}^0 \) , which is not affected by temperature, was –18.62 kJ mol–1. Changes of absorbance at 230 nm of ProTα with temperature can be assumed to resemble a transition in the secondary structure. The parameters characterizing the thermodynamics of unfolding, melting temperature (Tm), enthalpy (ΔHm), entropy (ΔSm) and heat capacity (ΔCp) were determined. The values obtained for Tm, ΔHm and ΔSm are smaller that those found for other globular proteins; ΔCp was found to be much smaller. These results suggest that ProTα exhibits some type of secondary structure under these conditions (10 mM glycine buffer, pH 2.4).

Protein stability Prothymosin α Difference spectroscopy Thermal denaturation Secondary structure 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

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  1. 1.Grupo de Fisica de Coloides y Polimeros, Departamento de Fisica Aplicada, Facultad de Física, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain
  2. 2.Departamento de Fisica de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain
  3. 3.Departamento de Bioquimica y Biologia Molecular, Facultad de Biologia, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain
  4. 4.Institute for Immunology and Thymus Research, 38667 Bad Harzburg, Germany

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