Structure and Dynamics of Disulfide Cross-Linked DNA Triple Helices
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- 作者：Scott E. Osborne ; Robert J. Cain ; and Gary D. Glick
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：February 12, 1997
- 年：1997
- 卷：119
- 期：6
- 页码：1171 - 1182
- 全文大小：321K
- 年卷期：v.119,no.6(February 12, 1997)
- ISSN：1520-5126
文摘
The design, synthesis, and characterization of two disulfidecross-linked intramolecular pyr·pur-pyr triplehelices (IV and V) is presented. Placement of a covalentcross-link from the Hoogsteen strand to the Watson-Crickduplex produces two fundamental changes in the cross-linked DNAsrelative to the parent sequence. First, formationof the cross-link results in an increase in the apparentpKa of the Hoogsteen cytosines by 1.5pKa units (to 8.6 and8.3 for IV and V, respectively) with a concomitant increase in thermalstability of ~40 
C at pH 7.4. Second, thecross-link enforces the triplex structure over a wide range of solutionconditions, including those that are physiologicallyrelevant (e.g., pH 7.4, 155 mM Na+, 37 C). CD andNMR measurements indicate that the cross-link does notsignificantly perturb the geometry of IV and V relative to theirunmodified counterpart. Because the disulfide cross-link effectively prevents conformational heterogeneity associated withpyr·pur-pyr triple helices containingC+·G-Cbase-triplets at neutral pH, constructs possessing this modificationcan serve as model systems to examine the structuraland thermodynamic aspects of triplex formation in vitro andto aid in the development of sequences that bind withhigher affinity and specificity.
C at pH 7.4. Second, thecross-link enforces the triplex structure over a wide range of solutionconditions, including those that are physiologicallyrelevant (e.g., pH 7.4, 155 mM Na+, 37 C). CD andNMR measurements indicate that the cross-link does notsignificantly perturb the geometry of IV and V relative to theirunmodified counterpart. Because the disulfide cross-link effectively prevents conformational heterogeneity associated withpyr·pur-pyr triple helices containingC+·G-Cbase-triplets at neutral pH, constructs possessing this modificationcan serve as model systems to examine the structuraland thermodynamic aspects of triplex formation in vitro andto aid in the development of sequences that bind withhigher affinity and specificity.