Torrence P F, Witkop B
Biochim Biophys Acta. 1975 Jun 2;395(1):56-66. doi: 10.1016/0005-2787(75)90233-6.
In order to find a poly(A)-poly(U) analog which could not form a triple-stranded complex and which would have a sufficiently high thermal stability to survive under physiological conditions, the interaction of poly(7-deazaadenylic acid) (poly(c-7A)) with modified polyuridylic acids was examined. Mixing curves constructed by the method of continuous variation, isosbestic points and thermal melting profiles proved that poly(c-7A) formed only 1:1 complex with polyribothymidylic acid and poly(5-bromouridylic acid) (Tm values of 50 and 72 degrees C respectively, in 0.15 M NaCl, 0.01 M KH2 PO4, 0.001 M MgCl2, pH7). In addition poly(c-7A) formed a 1:1 complex with poly(I) (Tm equals 22 degrees C in 0.46 M salt, pH 7), and presumed duplexes were observed in the interaction of poly(c-7A) with poly(dT), poly(2'-azido-2'-deoxyuridylic acid) and poly(2'-O-methyluridylic acid) (Tm values of 35, 32 and 41 degrees C respectively, in 0.10 M NaCl, pH7).
为了找到一种不能形成三链复合物且具有足够高的热稳定性以在生理条件下存活的聚（A）-聚（U）类似物，研究了聚（7-脱氮腺苷酸）（聚（c-7A））与修饰的聚尿苷酸的相互作用。通过连续变化法构建的混合曲线、等吸收点和热熔解曲线证明，聚（c-7A）仅与聚核糖胸苷酸和聚（5-溴尿苷酸）形成1:1复合物（在0.15 M NaCl、0.01 M KH2PO4、0.001 M MgCl2、pH7中，Tm值分别为50和72摄氏度）。此外，聚（c-7A）与聚（I）形成1:1复合物（在0.46 M盐、pH 7中，Tm等于22摄氏度），并且在聚（c-7A）与聚（dT）、聚（2'-叠氮基-2'-脱氧尿苷酸）和聚（2'-O-甲基尿苷酸）的相互作用中观察到假定的双链体（在0.10 M NaCl、pH7中，Tm值分别为35、32和41摄氏度）。
