Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster Germany.
Chembiochem. 2010 Jul 5;11(10):1443-50. doi: 10.1002/cbic.201000162.
The fluorescent 8-aza-2'-deoxyisoguanosine (4) as well as the parent 2'-deoxyisoguanosine (1) were used as protonated dCH(+) surrogates in the third strand of oligonucleotide triplexes. Stable triplexes were formed by Hoogsteen base pairing. In contrast to dC, triplexes containing nucleoside 1 or 4 in place of dCH(+) are already formed under neutral conditions or even at alkaline pH values. Triplex melting can be monitored separately from duplex dissociation in cases in which the third strand contains the fluorescent nucleoside 4. Third-strand binding of oligonucleotides with 4, opposite to dG, was selective as demonstrated by hybridisation experiments studying mismatch discrimination. Third-strand binding is more efficient when the stability of the DNA duplex is reduced by mismatches, giving third-strand binding more flexibility.
荧光 8-氮杂-2'-脱氧次黄嘌呤核苷（4）以及母体 2'-脱氧次黄嘌呤核苷（1）被用作寡核苷酸三链体中质子化 dCH(+)替代物。通过 Hoogsteen 碱基配对形成稳定的三链体。与 dC 不同，在中性条件下甚至在碱性 pH 值下，用核苷 1 或 4 替代 dCH(+)形成三链体。在第三链包含荧光核苷 4 的情况下，可以单独监测三链体的熔解，而无需监测双链体的解离。与 dG 相反，与寡核苷酸的第三链结合具有选择性，如通过研究错配区分的杂交实验所示。当 DNA 双链体的稳定性因错配而降低时，第三链体的结合更有效，从而使第三链体的结合更具灵活性。
