Department of Life, Health and Chemical Sciences, The Open University, UK.
Spectrochim Acta A Mol Biomol Spectrosc. 2012 Sep;95:270-5. doi: 10.1016/j.saa.2012.04.053. Epub 2012 Apr 23.
The interactions of two short aptamers to human and bovine serum albumins were studied by fluorescence spectroscopic techniques. Intrinsic fluorescence of BSA and HSA were measured by selectively exciting their tryptophan residues. Gradual quenching was observed by titration of both proteins with aptamers. Aptamers are oligonucleic acid or peptide molecules that bind a specific target and can be used for both biotechnological and clinical purposes, since they present molecular recognition properties like that commonly found in antibodies. Two aptamers previously selected against the MUC1 tumour marker were used in this study, one selected for the protein core and one for the glycosylated MUC1. Stern-Volmer graphs were plotted and quenching constants were estimated. Plots obtained from experiments carried out at 25 °C and 37 °C showed the quenching of fluorescence of by aptamers to be a collisional phenomenon. Stern-Volmer constants estimated for HSA quenched by aptamer A were 1.68 × 10(5) (± 5 × 10(3))M(-1) at 37 °C, and 1.37 × 10(5) (± 10(3))M(-1) at 25 °C; and quenched by aptamer B were 1.67 × 10(5) (± 5 × 10(3))M(-1) at 37 °C, and 1.32 × 10(5) (± 10(3))M(-1) at 25 °C. Results suggest that the primary binding site for aptamers on albumin is close to tryptophan residues in sub domain IIA.
两种短适体与人血清白蛋白和牛血清白蛋白相互作用的研究采用荧光光谱技术。通过选择性地激发色氨酸残基来测量 BSA 和 HSA 的固有荧光。通过用适体滴定两种蛋白质，观察到逐渐猝灭。适体是与特定靶标结合的寡核苷酸或肽分子，由于它们具有与抗体中常见的分子识别特性，因此可用于生物技术和临床目的。在这项研究中使用了两种先前针对 MUC1 肿瘤标志物选择的适体，一种针对蛋白质核心，一种针对糖基化 MUC1。绘制了 Stern-Volmer 图并估计了猝灭常数。在 25°C 和 37°C 下进行的实验得到的图表明，适体猝灭荧光是一种碰撞现象。在 37°C 下，适体 A 猝灭 HSA 的 Stern-Volmer 常数估计为 1.68×10(5)(±5×10(3))M(-1)，在 25°C 下为 1.37×10(5)(±10(3))M(-1)；在 37°C 下，适体 B 猝灭 HSA 的 Stern-Volmer 常数估计为 1.67×10(5)(±5×10(3))M(-1)，在 25°C 下为 1.32×10(5)(±10(3))M(-1)。结果表明，适体在白蛋白上的主要结合位点靠近亚域 IIA 中的色氨酸残基。
