title: Parallel-stranded DNA: enhancing duplex stability by the 'G-clamp' and a pyrrolo-dC derivative.
abstract: The new pyrrolo-dC derivative 4 tethered with an alkylamino side chain via a triazole linker was synthesized. Oligonucleotides containing the G-clamp 3 or the pyrrolo-dC derivative 4 were prepared. Oligonucleotide synthesis and deprotection under standard conditions led to unwanted side product formation. The side product was identified as an acrylonitrile adduct of the aminoalkyl side chain. Changing the synthesis and work-up conditions to fast-deprotection chemistry and performing β-elimination of the cyanoethyl group on the solid support yielded pure oligonucleotides. Oligonucleotide duplexes with parallel chain orientation were constructed incorporating dA·dT and isoG(d)·dC base pairs. Replacement of dC-residues by the G-clamp 3 led to extraordinarily stable duplexes (ΔT(m) = +11 °C for two incorporations) in ps DNA, while the pyrrolo-dC derivative 4 behaved like dC. Surprisingly, the G-clamp 3 forms an even more stable base pair with 2'-deoxyisoguanosine in DNA with parallel chain orientation than with 2'-deoxyguanosine in aps DNA.
authors.affiliation: Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstrasse 11, 48149 Münster, Germany.
authors.forename: Xin
authors.initials: X
authors.lastname: Ming
authors.forename: Ping
authors.initials: P
authors.lastname: Ding
authors.forename: Peter
authors.initials: P
authors.lastname: Leonard
authors.forename: Simone
authors.initials: S
authors.lastname: Budow
authors.forename: Frank
authors.initials: F
authors.lastname: Seela
mesh_terms: D003596:Cytosine / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry*; D015394:Molecular Structure; D009705:Nucleosides / Q000138:chemical synthesis; D011758:Pyrroles / Q000737:chemistry*
chemical_list: D009705:Nucleosides; D011758:Pyrroles; D006147:Guanine; D003596:Cytosine; D004247:DNA