MOST COMPACT HAIRPIN-TURN STRUCTURE EXERTED BY A SHORT DNA FRAGMENT, D(GCGAAGC) IN SOLUTION - AN EXTRAORDINARILY STABLE STRUCTURE RESISTANT TO NUCLEASES AND HEAT
MOST COMPACT HAIRPIN-TURN STRUCTURE EXERTED BY A SHORT DNA FRAGMENT, D(GCGAAGC) IN SOLUTION - AN EXTRAORDINARILY STABLE STRUCTURE RESISTANT TO NUCLEASES AND HEAT
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DOI：
10.1093/nar/22.4.576
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发表时间：
1994-02-25
影响因子：
14.9
通讯作者：
MIURA, K
中科院分区：
文献类型：
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作者：
HIRAO, I;KAWAI, G;MIURA, K
通过核磁共振波谱法确定了短 DNA 片段 d(GCGAAGC) 的三维结构，该片段表现出非常稳定的发夹结构。通过使用距离和扭转约束的分子建模获得了两种可能的模型。这两个模型中只有一个是正确的结构，可以清楚地解释所有的H-1化学位移。 d(GCGAAGC) 在 A(4) 和 A(5) 之间自行折叠，片段中的所有糖均采用 C2'-endo 构象。这种紧凑的分子通过 G(1)C(2)G(3)A(4) 和 A(5)G(6)C(7) 的每个 B 型螺旋链内定期广泛的碱基堆积相互作用以及两个 G-C 和一个 G(3)-A(5) 碱基对来稳定。该分子很难区分茎区和环区，因此我们将其归类为单链DNA产生的转角（发夹转角）结构。这种高度堆叠的结构表现出高热稳定性，并对大肠杆菌提取物和人血清中所含的核酸酶具有很强的抵抗力。
The three-dimensional structure of a short DNA fragment, d(GCGAAGC) exhibiting an extraordinarily stable hairpin structure was determined by nuclear magnetic resonance spectroscopy. Two possible models were obtained by molecular modelling using distance and torsion constraints. Only one of these two models is the correct structure, which can clearly explain all the H-1 chemical shifts. d(GCGAAGC) is folded back on itself between A(4) and A(5) and all the sugars in the fragment adopt the C2'-endo conformation. This compact molecule is stabilized by regular extensive base-stacking interaction within each B-form helical strand of G(1)C(2)G(3)A(4) and A(5)G(6)C(7), and by two G-C and one G(3)-A(5) base pairs. The molecule is hard to differentiate into stem and loop regions, so that we classify it as a turn (hairpin-turn) structure exerted by a single-stranded DNA. This highly stacked structure shows high thermostability and strong resistance against nucleases contained in E. coli extracts and in human serum.