Two-Repeat Human Telomeric d(TAGGGTTAGGGT) Sequence Forms Interconverting Parallel and Antiparallel G-Quadruplexes in Solution: Distinct Topologies, Thermodynamic Properties, and Folding/Unfolding Kin
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- 作者：Anh Tuâ ; n Phan and Dinshaw J. Patel
- 刊名：Journal of the American Chemical Society
- 出版年：2003
- 出版时间：December 10, 2003
- 年：2003
- 卷：125
- 期：49
- 页码：15021 - 15027
- 全文大小：197K
- 年卷期：v.125,no.49(December 10, 2003)
- ISSN：1520-5126
文摘
We demonstrate by NMR that the two-repeat human telomeric sequence d(TAGGGTTAGGGT)can form both parallel and antiparallel G-quadruplex structures in K+-containing solution. Both structuresare dimeric G-quadruplexes involving three stacked G-tetrads. The sequence d(TAGGGUTAGGGT),containing a single thymine-to-uracil substitution at position 6, formed a predominantly parallel dimericG-quadruplex with double-chain-reversal loops; the structure was symmetric, and all guanines wereanti. Another modified sequence, d(UAGGGTBrUAGGGT), formed a predominantly antiparallel dimericG-quadruplex with edgewise loops; the structure was asymmetric with six syn guanines and six anti guanines.The two structures can coexist and interconvert in solution. For the latter sequence, the antiparallel formis more favorable at low temperatures (<50 
C), while the parallel form is more favorable at highertemperatures; at temperatures lower than 40 C, the antiparallel G-quadruplex folds faster but unfoldsslower than the parallel G-quadruplex.
C), while the parallel form is more favorable at highertemperatures; at temperatures lower than 40 C, the antiparallel G-quadruplex folds faster but unfoldsslower than the parallel G-quadruplex.