Sen A, Maiti M
Biophysical Chemistry Laboratory, Indian Institute of Chemical Biology, Kolkata 700 032.
Indian J Biochem Biophys. 2002 Apr;39(2):106-12.
Interaction of sanguinarine with A-form RNA structures of poly(rI)poly(rC) and poly(rA).poly(rU) has been studied by spectrophotometric, spectrofluorimetric, UV melting profiles, circular dichroism and viscometric analysis. The binding of sanguinarine to A-form duplex RNA structures is characterised by the typical bathochromic and hypochromic effects in the absorption spectrum, increasing steady state fluorescence intensity, an increase in fluorescence quantum yield of sanguinarine, an increase in fluorescence polarization anisotropy, an increase of thermal transition temperature, an increase in the contour length of sonicated rod-like RNA structure and perturbation in circular dichroic spectrum. Scatchard analysis indicates that sanguinarine binds to each polymer in a non-cooperative manner. Comparative binding parameters determined from absorbance titration by Scatchard analysis, employing the excluded site model, indicate a higher binding affinity of sanguinarine to poly(rI).poly(rC) structure than to poly(rA).poly(rU) structure. On the basis of these observations, it is concluded that the alkaloid binds to both the RNA structures by a mechanism of intercalation.
通过分光光度法、荧光分光光度法、紫外熔解曲线、圆二色性和粘度分析研究了血根碱与聚（rI）聚（rC）和聚（rA）聚（rU）的A-型RNA结构的相互作用。血根碱与A-型双链RNA结构的结合表现为吸收光谱中典型的红移和减色效应、稳态荧光强度增加、血根碱荧光量子产率增加、荧光偏振各向异性增加、热转变温度升高、超声处理的棒状RNA结构轮廓长度增加以及圆二色光谱的扰动。Scatchard分析表明血根碱以非协同方式与每种聚合物结合。采用排除位点模型，通过Scatchard分析从吸光度滴定确定的比较结合参数表明，血根碱对聚（rI）聚（rC）结构的结合亲和力高于对聚（rA）聚（rU）结构的结合亲和力。基于这些观察结果，得出结论：生物碱通过嵌入机制与两种RNA结构结合。
