Structure and energetics of a hexanucleotide duplex with stacked trinucleotide ends formed by the sequence d(GAATTCGCG).
Structure and energetics of a hexanucleotide duplex with stacked trinucleotide ends formed by the sequence d(GAATTCGCG).
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具有由序列 d(GAATTCGCG) 形成的堆叠三核苷酸末端的六核苷酸双链体的结构和能量学。
DOI：
10.1021/bi00532a005
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发表时间：
1982
期刊：
影响因子：
2.9
通讯作者：
Breslauer,KJ
中科院分区：
文献类型：
--
作者：
Patel,DJ;Kozlowski,SA;Marky,LA;Rice,JA;Broka,C;Itakura,K;Breslauer,KJ
Dinshaw J. Patel,* Sharon A. Kozlowski, Luis A. Marky, Janet A. Rice, Chris Broka, Keiichi Itakura, and Kenneth J. Breslauer abstract: Nuclear magnetic resonance (NMR) and differ-ential scanning calorimetry (DSC) have been used to inves-tigate structural and energetic features of the helix-to-coil transition of the duplex formed by the partially self-complementary sequence d (GAATTCGCG)(henceforth called 9-mer). These results are compared with those obtained from a corresponding study on the helix-to-coil transition of the duplex formed by the fully self-complementary sequence d-(GGAATTCC)(henceforth called 8-mer). The two sequences contain a common GAATTC hexanucleotide duplex with this core flanked by d (GCG) trinucleotide ends in the 9-mer and by dG* dC base pairs in the 8-mer duplex. The NMR parameters for the 9-mer reveal formation of the hexanucleotide core duplex and stacking of the unpaired bases at the tri-nucleotide ends. The imino proton line widths suggest that under the conditions of the NMR experiment and at low temperature the 9-mer duplexes aggregate through pairing of the complementary ends. DSC on both the 8-mer and 9-mer duplex in 1 M NaCl reveals that the calorimetric transition enthalpies are essentially equal [~ 60 kcal (mol of double strand)-1] despite a 6.2 C higher melting temperature, Tm, for the 8-mer relative to the 9-mer duplex. From a comparison of the model-dependent van’t Hoff and model-independent calorimetric enthalpies we conclude that the helix-to-coil transition of the 8-mer approaches two-state behavior while the corresponding 9-mer transition involves intermediate states. We assign the cooperative component of the 9-mertransition to disruption of the hexanucleotide duplex core with the re-maining noncooperative component beingassociated with the disruption of the stacked ends. e early research on the helix-coil transition of DNA and RNA oligonucleotide sequences focused on fully base-paired duplexes (Cross & Crothers, 1971; Patel, 1974; Breslauer et f From BellLaboratories, Inc., Murray Hill, New Jersey 07974
