Complete disproportionation of duplex poly(dT)*poly(dA) into triplex poly(dT)*poly(dA)*poly(dT) and poly(dA) by coralyne.
Complete disproportionation of duplex poly(dT)*poly(dA) into triplex poly(dT)*poly(dA)*poly(dT) and poly(dA) by coralyne.
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DOI：
10.1093/nar/30.4.983
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发表时间：
2002-02
影响因子：
14.9
通讯作者：
Matjaž Polak;N. Hud
中科院分区：
文献类型：
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作者：
Matjaž Polak;N. Hud
Coralyne是一种小的新月形分子，已知可以插入双链体和三链体DNA。我们报道了Coralyne可引起双链体poly（dT）*poly（dA）的完全和不可逆的变性。也就是说，Coralyne导致双链体poly（dT）*poly（dA）的链重新分配成等摩尔当量的三链体poly（dT）*poly（dA）*poly（dT）和poly（dA）。如果将样品保持在4 ℃，则在加入coralyne后，Poly（dT）*Poly（dA）将保持为双链体数月。然而，当加热到35摄氏度以上时，结晶容易发生，并且不会被随后的冷却逆转。用coralyne滴定poly（dT）*poly（dA）表明，对于初始双链体的每8个碱基对，低至1摩尔当量的coralyne有利于双链化。我们还发现，聚（dA）形成一个自我结构的存在下，coralyne的熔融温度为47摄氏度，为我们的研究条件。这种聚（dA）自身结构以与三链体聚（dT）* 聚（dA）* 聚（dT）相当的亲和力结合coralyne。一个工作图分析表明，聚（dA）的自我结构嵌入的最大水平是0.25 coralyne分子每腺嘌呤基地。这符合具有A*A碱基对的聚（dA）双链体结构的最近邻排除原理。我们建议，双链体的coralyne的双链体的pactionation是由三链体和聚（dA）的自身结构，具有结合常数coralyne大于双链体聚（dT）* 聚（dA）的促进。
Coralyne is a small crescent-shaped molecule known to intercalate duplex and triplex DNA. We report that coralyne can cause the complete and irreversible disproportionation of duplex poly(dT)*poly(dA). That is, coralyne causes the strands of duplex poly(dT)*poly(dA) to repartition into equal molar equivalents of triplex poly(dT)*poly(dA)*poly(dT) and poly(dA). Poly(dT)*poly(dA) will remain as a duplex for months after the addition of coralyne, if the sample is maintained at 4 degrees C. However, disproportionation readily occurs upon heating above 35 degrees C and is not reversed by subsequent cooling. A titration of poly(dT)*poly(dA) with coralyne reveals that disproportionation is favored by as little as one molar equivalent of coralyne per eight base pairs of initial duplex. We have also found that poly(dA) forms a self-structure in the presence of coralyne with a melting temperature of 47 degrees C, for the conditions of our study. This poly(dA) self-structure binds coralyne with an affinity that is comparable with that of triplex poly(dT)*poly(dA)*poly(dT). A Job plot analysis reveals that the maximum level of poly(dA) self-structure intercalation is 0.25 coralyne molecules per adenine base. This conforms to the nearest neighbor exclusion principle for a poly(dA) duplex structure with A*A base pairs. We propose that duplex disproportionation by coralyne is promoted by both the triplex and the poly(dA) self-structure having binding constants for coralyne that are greater than that of duplex poly(dT)*poly(dA).