The detection of B-form/A-form junction in a deoxyribonucleotide duplex
The detection of B-form/A-form junction in a deoxyribonucleotide duplex
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DOI：
10.1016/s0006-3495(96)79527-9
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发表时间：
1996-12-01
影响因子：
3.4
通讯作者：
Zimmer, C
中科院分区：
文献类型：
--
作者：
Ivanov, VI;Minchenkova, LE;Zimmer, C
用圆二色谱研究了14-Meric脱氧寡核苷酸双链d-(ACCCCCTTTTTTG)-d-(CAAAAAAAGGGGGGGGGGT)在水/三氟乙醇(TFE)溶液中从B-构象到A-构象的转变。TFe含量的增加会导致两步B-A相变。在第一步中，直到73%的TFE，A型由富含GC的部分生成；在第二步，73-82%的TFE，富含AT的部分转移到A型。由此，我们认为在73%的TFE附近存在BIA结。BIA连接的出现已被地塞霉素A和netropsin的使用直接证实，这两种已知的配体选择性地与B-DNA的AT片段结合。可以看出，两种配体都抑制了亲B部分A型的形成。B/A结的自由能值估计为2.1。KCAL/摩尔，这与聚合物DNA的已知数据很好地吻合。所获得的结果可能与最近发表的关于DNA与HIV逆转录酶的复合体中出现B/A连接的X射线数据具有生物学相关性。
The transition of the 14-meric deoxyoligonucleotide duplex d-(ACCCCCTTTTTTTG)-d-(CAAAAAAAGGGGGT) from the B- to the A-conformation in water/trifluorethanol (TFE) solution was studied with the use of circular dichroism. An increase in the fraction of TFE induces a two-step B-A transition. in the first step, up to 73% TFE, the A-form is generated from the GC-rich part; in the second step, 73-82% TFE, the AT-rich part shifts to the A-form. By this we suggest the existence of a BIA junction near 73% TFE. Emergence of the BIA junction has been directly confirmed with the use of distamycin A and netropsin, ligands known to selectively bind to AT stretches of B-DNA. it can be shown that both ligands suppress formation of the A-form in the B-philic part. The free energy value for the B/A junction was estimated to be 2.1. kcal/mol, which agrees well with known data for polymeric DNAs. The obtained results may have biological relevance in connection with recently published x-ray data about the occurrence of the B/A junction in the complex of DNA with reverse transcriptase of HIV.