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|Title||Thermodynamic Analysis of Thymoquinone Binding to Human Serum Albumin and Denaturation Study of the Resultant Complex|
|Title in Arabic||تحليل الديناميكا الحرارية لارتباط الثايموكوينون مع مصل بروتين الدم البشري ودراسة التخثر للمركب الناتج|
There is an increasing interest of therapeutic effects of Thymoquinone (TQ) which is the main constituent of Nigella Sativa (N.S) essential oil, the interaction between Thymoquinone and Human Serum Albumin (HSA) - as a possible carrier of this drug in vivo - were investigated by Fluorescence spectra. The association process resulted in a change in the intrinsic fluorescence. The emission spectra were analyzed according to two models described by Stern-Volmer and Scatchard equations; to obtain the association constant (Ka) values in the temperature range of 25-50oC and (pH7.0). The results showed that the association constants were temperature dependent. The value of Ka at 25°C was 1.70×104 M–1. Using fluorescence quenching spectroscopy, one mole of TQ was found to bind one mole of HSA. Moreover, the thermodynamic parameters for the interaction HSA/TQ, the enthalpy (ΔH) and the entropy change (ΔS) were estimated from Van't-Hoff plots to be -16.22 KJ/mol and 34.08 J/mol.K, respectively. The thermodynamic analysis of the HSA-TQ complex formation shows that the binding was enthalpically and entropically driven, spontaneous and that hydrophobic interactions are the predominant intermolecular forces stabilizing the complex. The chemical denaturation of HSA by urea (8M) and at pH7.0 were studied in presence and absence of TQ at room temperature (nearly25°C). The conformational stability of HSA also was explained depending on the Gibbs free energy change ΔG°D(H2O) which was estimated in two above states by Van't-Hoff method. Moreover, the denaturant m-value was determined considering the two-state process. In addition, data analysis was carried out based upon this consideration. It is found from the results, because of the high value of denaturant m-value; the denaturation by urea in absence of TQ was faster.
|Publisher||الجامعة الإسلامية - غزة|
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