Fluorescence spectroscopy evaluation of fibrinogen–β-estradiol binding

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• 作者：Só ; nia Gonç ; alves ; Nuno C. Santos ; J. Martins-Silva ; Carlota Saldanha
• 关键词：Fibrinogen ; β ; -estradiol ; Fluorescence ; Binding constant ; Quenching
• 刊名：Journal of Photochemistry and Photobiology B: Biology
• 出版年：2007
• 出版时间：1 February 2007
• 年：2007
• 卷：86
• 期：2
• 页码：170-176
• 全文大小：244 K

文摘

Fluorescence spectroscopy experiments were performed in order to study conformational changes induced by the binding of β-estradiol to fibrinogen at different ligand concentrations. The association constant (K_a) obtained for the fibrinogen–β-estradiol binding was 6.47 × 10⁶ M⁻¹, indicating a high affinity interaction. Fluorescence quenching experiments showed that approximately 30 % of the tryptophan residues in the protein quaternary structure are accessible to ionic quenchers. The extent of quenching in the absence and presence of β-estradiol was maximum for cesium ions and minimum for iodide, suggesting the presence of negatively charged residues in the vicinity of the tryptophan residues. The quenching parameters obtained at different β-estradiol concentrations show alterations that confirm a conformational change, possibly due to a discrete reorganization of tryptophan residues during fibrinogen–β-estradiol binding. This binding may be responsible for the effects of β-estradiol on the decrease of erythrocyte aggregation and on cardiovascular risk reduction.